To provide a waterproof pan in which breakage at the time of transport and at the time of assembling can be prevented by integrally reinforcing a washing place and a bath tub, or supporting the same.

A waterproof pan comprises a waterproof pan main body 1 where a washing place 11 and a style support part 12 of a bath tub are integrally formed and a reinforcement frame 2 provided at the back of the waterproof pan main body 1. A reinforcing material 21 provided at the back of the washing place of the reinforcement frame 2 toward the style support part 12 is extended to right under the inner end of the style support part 12, a support rod 23 is erected on the extended end part, and the inner end of the style support part 12 is supported by the support rod 23.