PURPOSE: To make a unit bath resistant to soil and easy to clean even when soiled.

CONSTITUTION: A fluororesin layer 9 is formed over the inner surface of each wall panel 3 constituting a unit bath or a shower unit, or on both the inner surface of each wall panel 3 and the inner surfaces of floor and ceiling panels, and a tongue 7 and a groove 8 are formed at the junction of time wall panels 3. The tongue 7 is fitted into the groove 8 with packing 10 put in the junction, and caulking compound 4 is packed inside the junction to make a watertight connection between time wall panels 3.