牛甘は．「牛飼」とも書かれ． 古代において牛の飼養・飼育及び管理を行っていた者及びその集団の名称であると考えられる。本論では． 牛甘（飼）に関連する文献史料を紹介した上で. (1)牛形埴輪. (2)装飾古墳の牛と想定できる図文. (3)高旬麗壁画古墳で描かれた牛図． を比較分析の対象として． その共通点と相違点を抽出することで． 牛の渡来と牛甘 （飼） の特性について考察を行った。牛及びその飼育や管理の技術は. 5世紀後半以前に． 馬及びその飼育や管理の技術と一連のものとして． 朝鮮半島から渡来した可能性が高い。 しかしながら． 古代日本 では． 馬の生産に比べて． 牛は極めて少なかったことが指摘でき． むしろ． その利用が皇族・貴族のための薬としての牛乳 ・ 乳製品の生産に限定されていたため， 数多くの牛の生産の必要がなかったといえる。 渡来当初． 牛は馬甘（飼）によって馬と一緒に飼育されていた可能性が高く． 馬甘（飼） と牛甘（飼）は明確に分化された存在ではなかったと考えられる。 このことが． 古代日本において， 牛甘（飼）が専門集団として発達しなかった理由と考えられ． むしろ． 牛甘（飼）の特性であったといえる。また， 牽牛織女説話も， 牛の渡来と大差ない時期に． 牛の飼育と一連の文化複合として． 朝鮮半島から日本に伝来し， 今日の七夕説話として定着した可能性が高いといえる。

Ushikai (written牛甘 or 牛飼) is an ancient name for either individual cowherds or a group. I introduced a series of bibliographic materials related to Ushikai in this paper, comprising: (1) A bovine-shaped Haniwa; (2) A drawing from ornamented tombs that is thought to be of a bovine, and (3) Bovine drawing on Goguryeo tomb murals. I identify the common features and differences amongst these materials, and discuss the arrival of cattle in Japan and the characteristics of Ushikai based on these findings. Cattle as well as raising and management technologies first arrived in Japan before the late 5th century from the Korean Peninsula, almost certainly at the same time and in the same context as horses. Evidence suggests, however, that only very limited cattle production was practiced in ancient Japan compared to horse production; it appears to have been little need for large numbers of cattle as their use at this time was limited to milk and dairy product production for use as medicines for the royal family and aristocrats. It is also highly likely that cattle were initially reared by Umakai alongside horses when first introduced to Japan, and that Umakai and their counterparts were not clearly distinct from one another. This is considered as one reason why the Ushikai of ancient Japan did not develop into a group devoted to entirely to cattle husbandry; rather, the absence of this developmental characteristic appears to define the group. Finally, it is also highly likely that the legend of the cowherd and the weaver girl was transmitted to Japan from the Korean Peninsula as a cultural complex related to the cattle rearing around the same time as the importation of these animals. This legend has become part of popular culture as a modern-day Tanabata (Star Festival) narrative.