To provide a sanitary unit having an optimized structure including all required facilities and functioning without extremely reducing an ergonomically usable space inside a small room.

The sanitary unit for a vehicle, especially a rolling stock, includes the small room 3 having at least a toilet bowl 2 or a wash bowl 6. In the sanitary unit, a clean water tank 4 and a sewage reserving tank 5 are vertically disposed at each corner of a rectangular limit volume 1, respective tanks 4 and 5 have a wedge shaped outer wall matching with a shape of the corner of the rectangular limit volume 1, and a side facing to the small room 3 has inner walls 4a and 5a substantially matching with the shape of the small room 3.