PURPOSE: To enable ventilating efficiency in a bathroom to be improved, and obviate the necessity of suction vent in the bathroom door, and prevent the reverse current of moisture into rooms or the like except, the bathroom from being generated.

CONSTITUTION: On a floor surface 22, a setting section 24 for setting a washing machine 23 is set, and on the floor surface 22 positioned at the setting section 24, a suction port 26 for sucking up open air is formed. To cover the setting section 24, a water-proof pan 27 for mounting the washing machine on it is set, and on the side wall surface 27b of the water-proof pan 27, opening apertures 30, 30,... communicated with the suction port 26 are formed. The opening apertures 30, 30... can be opened or closed.