The angioarchitecture of the skin in the SD strain rat was investigated by scanning electron microscopy using resin cast. The neck part of rat skin was composed of 3 layers of vascular networks: the first layer (superficial layer), the second layer (middle layer), and the third layer (deep layer). Two types of capillary architectures were present around the hair follicle: small architectures composed of random network and large architectures composed of 3 parts distinguished by the construction of network. The large architecture, the capillary of hair papilla and the capillary network of sebaceous gland was thought to compose one circulation unit. The afferent vessels into such units branched from Kandelaberarterie-Petersen occurring from the 3rd layer, ascended to the 2nd layer, then descended to the bottom of the network and composed the capillary architecture. There were 2 types of efferent vessels from such circulation unit. They occurred from superficial and deep part, respectively, of the vascular architecture around the hair follicle and descended straight to the 3rd layer. The presence of straight vessels between the 2 nd and 3 rd layer, and the simple arrangement of vascular layers were thought to be characteristic of the angioarchitecture of the rat skin.