PURPOSE: To make it possible to easily operate a low tank with a wash-hand basin by burying the low tank with the wash-hand basin in a wall within range of being capable of controlling a draining valve controlling handle lever for the low tank as a side wall to a user sitting on a western-style closet.

CONSTITUTION: A western-style closet A consisting of a closet bowl 20, a closet seat 21 and a closet cover 22 is mounted on a floor of a lavatory. The rear side of low tank B is so buried in a wall C within range of being capable of controlling a draining valve controlling handle lever for the low tank B with the wash-hand basin by a user sitting on the closet A that a part of a sink section 3a of a wash-hand section 3 is a position projected from the wall C. According to the constitution, the user can easily and surely control a handle- lever without tuning his or her hand to his or her rear side.