To house an external piping in a housing space section in such a manner that the projection of the piping from the external surface of a wall panel constituting a unit bath is not allowed without using any special waterproof pan for the unit bath.

A unit bath is constituted of a waterproof pan 1, a spandrel wall panel 2 provided on the peripheral edge of the pan 1, a horizontal panel 3 horizontally attached to the upper end section of the spandrel wall panel 2, and a wall panel 4 attached to the edge section of the horizontal panel to the ceiling. The horizontal and spandrel wall panel 3 and 2 are coupled by a bracket 7 provided with a housing space section 6 for housing external piping 5.