PURPOSE: To facilitate inspection and maintenance.

CONSTITUTION: A counter 2 protruded to the outside is attached to an opening edge on the upper face of a bathtub 1. An overflow hole 4 is formed in the upper part of a side wall of the bathtub 1. A water discharge nozzle 5 is provided on the upper face of the counter 2 in the upper part of the overflow hole 4. A filter 6 is provided on the side of the bathtub 1 in the lower part of the counter 2. The overflow hole 4 and the water discharge nozzle 5 are connected through the filter 6. An inspection port 7 is provided in the counter above the filter 6. The water discharge nozzle 5 and the inspection port 7 are covered with a cover 8 so as to be freely detachable and attachable. Although the filter 6 is provided below the counter 2, the inspection and maintenance can be executed by detaching the cover 8 for covering the water discharge nozzle 5 and the inspection hole 5 above the filter 6. The water discharge nozzle 5 and the inspection port 7 can be covered with a common cover 8.