To drain hot water without half rising or inclining a hip bath apparatus and to reduce the load of a user by providing a drain port with opening and closing door on a tray in the hip bath apparatus for putting hot water in the tray adhered to the open part of a stool and dipping the hip in the hot water to wash it.

In use, the end part of an air pipe 5 is inserted to an air pipe insert hole 6 and engagingly locked by a locking wall 7, and the tip of the air pipe 5 is arranged under a desired position such as the anus and adjusted so that the desired part is exposed to the air bubbles blown out from the air pipe 5. An opening and closing door 9 is lowered to close a drain port 8, a collar 3 is engagingly locked by the upper surface of the mouth part of a stool 1 to mount a tray 2 on the stool 1, and hot water is then put therein. A user sits on the tray 2 in this state, and dips the hips in the hot water to wash it. When the washing is ended, the handle 10 of the opening and closing door 9 is held and raised to discharge the hot water within the tray 2 through the drain port 8. Accordingly, the user can easily and smoothly discharge the drain water after washing.