PURPOSE: To constitute the bathtub so that the aged and physically handicapped persons can taken a bath without the help of a person by forming an opening part through which the person can go in and out to the inside and the outside of a bathtub on the side part of the bathtub, and providing a closing means for closing this opening part so as to be freely openable and closeable.

CONSTITUTION: As for a bathtub 1, when a door 3 is opened, only a small projection is left between the bottom face of the inside of the bathtub 1 and the floor surface of an external bathroom, and by a roughly usual walking action, a person can go in and out to and from the bathtub 1, therefore, an action for striding over an edge of the bathtub 1 can be made unnecessary. Also, when the door 3 is closed and locking metallic fixtures 6, 7 are locked, an opening part 2 is sealed up tightly, therefore, the inside can be filled with hot water in the same way as a regular bathtub.