岡山県倉敷市矢部にある 楯築遺跡（たてつきいせき）／楯築墳丘墓 は、弥生時代後期（2世紀後半）に築かれた、日本最大級の弥生墳丘墓です。 全長約83メートル、高さ約4〜5メートルという規模を誇り、弥生から古墳への移行期を象徴する遺跡として、国の史跡に指定されています。

The Tatezuki Site (Tatezuki Iseki)/Tatezuki Tumulus in Yabe, Kurashiki City, Okayama Prefecture, is one of Japan’s largest Yayoi period tumuli, constructed during the late Yayoi period (late 2nd century AD). Boasting dimensions of approximately 83 metres in length and 4 to 5 metres in height, it is designated as a National Historic Site, symbolising the transitional period from the Yayoi to the Kofun era.

2025/08/23撮影

王墓の丘史跡公園（岡山県倉敷市）

巨石と神話を伝える場所
墳丘の頂上には、木棺を取り囲むように 5つの巨石（立石） が立てられており、古代の祭祀場とも考えられています。ここからは 人の顔に見える文様を刻んだ特殊器台 や、渦巻き模様を持つ「弧帯文石（重要文化財）」が出土しました。これらは葬送儀礼や宗教観を知る手がかりとなり、纏向遺跡（奈良）とも関連が指摘されています。また、地元には「温羅伝説」が伝わり、吉備津彦命が温羅と戦う際、この山に石楯を築いたとされています。遺跡名「楯築」もここに由来します。

A Site Preserving Megaliths and Mythology
At the summit of the burial mound, five standing stones (menhirs) are erected encircling a wooden coffin, suggesting this may have been an ancient ritual site. Excavations here yielded a special vessel stand carved with a pattern resembling a human face, and a spiral-patterned “arc-band stone” (designated an Important Cultural Property). These provide clues to funeral rites and religious beliefs, with connections also suggested to the Mamakō Site (Nara). Furthermore, the local ‘Ōra legend’ is passed down, stating that when Kibitsuhiko no Mikoto fought Ōra, he built a stone shield on this mountain. The site name ‘Tatezuki’ (Shield-Built) derives from this.


「楯築神社の旋帯文石（たてつきじんじゃのせんたいもんせき）」有形文化財/重要文化財、弥生時代、岡山県倉敷市（日本遺産ポータルサイト）

楯築神社の御神体である旋帯文石は、その形や表面に彫られた文様から亀石とも呼ばれています。石の表面には全面に特殊な帯状曲線入組文様が飾られ、正面には人間の顔のような彫り込みがみられます。遺物の呪術的性格を物語るこの特異な文様は、弥生時代から古墳時代への移行期に首長の墓に供えられた特殊器台にみられるものと類似しています。

吉備津彦命が温羅との戦いに使った空飛ぶ乗り物とも伝えられている。楯築遺跡の上に鎮座する楯築神社の御神体で、「弧帯文石」とも呼ばれる。全面に帯状の弧を描く文様が刻まれ、正面には人の顔が造り出されている。弥生時代の石造彫刻として最も優れたものである。

The spiral-band pattern stone, the sacred object of Tatezuki Shrine, is also known as the Turtle Stone due to its shape and the patterns carved upon its surface. The stone’s surface is entirely adorned with a distinctive banded, curved interlaced pattern, while the front features carvings resembling a human face. This distinctive pattern, indicative of the artefact’s magical nature, resembles those found on specialised vessel stands placed in chieftain’s tombs during the transition from the Yayoi to the Kofun period.

It is also said to be the flying vehicle used by Kibitsuhiko no Mikoto in his battle against Ōra. It is the sacred object enshrined at Tatezuki Shrine, which stands atop the Tatezuki ruins, and is also called the “Arc-band Pattern Stone”. A pattern of band-shaped arcs is carved across its entire surface, and a human face is carved on its front. It is the most outstanding example of Yayoi period stone sculpture.


生成AIでトレースした画像。


生成AIで復元した顔。まるで、ジョジョの石仮面。。

発掘と保存の歩み
1970年代以降、岡山大学や倉敷市によって7次にわたる調査が行われ、墓壙（ぼこう）や副葬品（鉄剣・ガラス玉など）が確認されました。ただし、宅地造成や給水塔建設で一部が破壊されるなど、保存の難しさも経験してきました。現在は神社弧帯文石を守る収蔵庫が設けられ、文化財として大切に保護されています。

The History of Excavation and Preservation
Since the 1970s, seven phases of investigation have been conducted by Okayama University and Kurashiki City, confirming the presence of burial pits and grave goods (including iron swords and glass beads). However, challenges in preservation have been encountered, such as partial destruction during land development and the construction of a water tower. Presently, a storage facility safeguarding the shrine’s arc-band patterned stone has been established, and it is carefully protected as a cultural asset.


岡山大学考古学研究室の図を参考に図を作成。

邪馬台国論争との関わり
楯築遺跡の築造は、卑弥呼の時代と同時期。吉備地方はヤマト政権と並ぶ有力勢力を持っていたとされ、この遺跡は 「邪馬台国＝吉備説」 を支える根拠のひとつにもなっています。独自の祭祀文化と巨大な墳丘墓の存在は、古代吉備王国の力を示すものです。

Connection to the Yamataikoku Debate
The construction of the Tatezuki Ruins coincided with the era of Himiko. The Kibi region is believed to have possessed a powerful force rivalling the Yamato regime, and this site serves as one piece of evidence supporting the ‘Yamataikoku = Kibi Theory’. The existence of its unique ritual culture and massive burial mounds demonstrates the power of the ancient Kibi Kingdom.

楯築遺跡は、
・日本最大級の弥生墳丘墓
・巨石祭祀と特殊土器を伴う独自の宗教文化
・温羅伝説と結びつく歴史的景観
・古墳時代や邪馬台国論争に直結する考古学的価値
を持つ、吉備を代表する遺跡です。倉敷観光の際には、ぜひこの地の古代史にも触れてみてはいかがでしょうか。

楯築遺跡
住所：岡山県倉敷市矢部 [Google Maps]
形状：双方中円形墳丘墓
規模：全長83m（推定）、円丘部直径49m
出土：鉄剣・首飾・ガラス玉・小管玉
築造：弥生時代後期後葉（2世紀）
指定：国の史跡「楯築遺跡」、国の重要文化財（弧帯文石）

Tatetsuki Site – Wikipedia

Tatetsuki Site (楯築遺跡, Tatetsuki Iseki) is a Yayoi period burial mound, located in the Yabe neighborhood of the city of Kurashiki, Okayama Prefecture, in the San’yō region of Japan. The tumulus was designated a National Historic Site of Japan in 1981. It is one of the largest Yayoi period graves in Japan.

The Tatetsuki tumulus is roughly 43 meters in diameter and four to five meters in height and has rectangular projections on the northeast and southwest sides. At the top of the tumulus, five megalithic stones surround the burial chamber, which contained a wooden coffin. On the slopes, there were about 20 stone rows with a height and width of more than one meter, on the exposed surface of the ground. However, the protruding part on the northeast side has been mostly destroyed due to the construction of the housing complex. Today, only a portion remains, extending for about ten meters. Its upper surface is about three to four meters wide. The front of the protrusion descends on a rather steep slope by about two to three meters and reaches a path running from east to west. Pebbles, similar to fukiishi, are placed in double and triple layers. The protruding part on the southwest side extends for about 20 meters and has a long, narrow ridge that is several meters wide and about two meters high. Both sides of the tip are rounded and a large row of stones is attached to the tip. A water tower now stands on the western part. It is possible that the tumulus was surrounded by a moat, which is now filled in.

Between 1976 and 1986, six archaeological excavations were conducted by the Archeology Laboratory of the Faculty of Letters, Okayama University. Two burial chambers were confirmed, and a wooden coffin was buried 1.5 meters underground in the center of the top of the mound. The excavated wooden coffin was about two meters long and 0.7 meters wide, and the bottom of the coffin was covered with 30 kilograms of vermilion. No bones were found, and only two tooth fragments were unearthed. The wooden coffin was housed in a wooden outer box with a total length of 3.5 meters and a total width of 1.5 meters. Grave goods were placed in the outer box and included one iron sword, two necklaces, many glass beads, and small tube beads. These artifacts are now housed in the Okayama University Archaeological Museum. In addition, another burial facility was discovered nine meters southeast of the central burial chamber, but only a small amount of vermillion was found and no grave goods were excavated. The paucity of burial goods is thought to be influenced by the burial customs of the period, rather than being related to authority or wealth.

In the protruding portion that was destroyed during the construction of the housing complex an array of vermilion-lacquered pot-shaped earthenware was discovered. Based on these pots and other pottery fragments found throughout the tumulus, it is believed that this site was a burial mound for chieftains of the Kingdom of Kibi during the late Yayoi period (late 2nd century to early 3rd century). After the end of the Civil War of Wa at the end of the 2nd century, large-scale burial mounds began to appear along the coast of the Seto Inland Sea, which includes this area. The fact that such large burial mounds were built before the Kofun period suggests that there was a large political power in this area that used special vessels and jars for funerary ceremonies. Later, in the middle of the Kofun period, Tsukuriyama Kofun, Sakuyama Kofun and other large keyhole-shaped burial mounds were constructed in the vicinity of this site.

On the top of the mound was stone carved with a pattern of swirling lines and discs, known as the Sentaimon-seki (旋帯文石). This pattern is of the same kind as found on special vessel stands used for ritual ceremonies in the Yayoi period. This stone has been passed down from generation to generation at Tatetsuki Shrine, which existed until the beginning of the Taisho period and is now housed in a storehouse near the ruins. This is called a “dense arc belt pattern stone”, and similar arc-patterned discs have been found at the Makimuku ruins in Sakurai, Nara. The stone is designated a National Important Cultural Property.

The Tatetsuki Tumulus is located in the Ohaka-no-oka Historic Site Park which includes the Ohakayama Kofun and the Hibata Temple Ruins. It is located about 30 minutes on foot from Kibitsu Station on the JR West Kibi Line.

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