The present article is an attempt to clarify in what way the Kamakura Bakufu perceived and took on and made to function police protection authority for the various provinces. There were two aspects to the authority gained by Shogun Minamoto-no-Yoritomo in 1190. The first involved the protection of the capital city of Kyoto, the suppression of insurrection, and the arrest of murderers by provincial constables (shugo 守護) invested with authority exceeding the powers of individual land proprietors (ryoshu 領主). The other aspect involved police action against such crimes as night raiding and the like by Bakufu vassals (gokenin 御家人) ; it ensured and protected the law enforcement rights of land proprietors with that authority. At that time, it was Yoritomo who was most interested in this authority, to be able to establish his positions as the "leader (toryo 棟梁) of the warrior class" and bestow his vassals a place in the societal framework. However, with end of the line of Minamoto 源 Shoguns and the collapse of the military power of the imperial court as a result of its clash in 1221 with the Bakufu, the latter's vassals rose as the main force in carrying out police protection in the province, Consequently, the Bakufu had to come up with a more efficient and organized system of law enforcement. In its legal code, the Goseibai-Shikimoku 御成敗式目 the law enforcement jurisdiction of shugo provincial constables was broadened and their ultimate right to enter (i. e., police) the lands of locally-based warrior proprietors (jito 地頭) was also guaranteed. Then, after the investiture of prince Munetaka 宗尊 as Shogun, shugo, jito, and the residents of jito proprietorships were organized vertically into a Bakufu law enforcement hierarchy, while a horizontal organization made up of neighboring jito was established, thus forming a consolidated peace keeping system. Nevertheless, when the Bakufu attempted to take effective step in law enforcement to deal with the worsening problems caused by outlaw groups of warriors (akuto 悪党), sole reliance on the strength of its loyal vassals reached its limits. This is why in the "benevolent acts" (tokusei 徳政) of the Koan 弘安 era (1278-88), all land proprietors throughout Japan were mobilized in the law enforcement effort. It turned out, however that the ultimate framework of this policy came to include only Bakufu vassals. And even during the regency of Hojo Takatoki (1316-26), a scheme to mobilize residents of the aristocratic complete jurisdictional proprietorships (honjo-ichien-chi 本所一円地) also failed. Throughout its existence the Bakufu was unable to go beyond its initial framework for protecting the provinces with its corps of vassals, and the problem of how to mobilize all of the country's land proprietors into a system of law enforcement became an issue for the next generation to solve.