PURPOSE: To prevent the floating of a body when an aged person bathes and easily goes into or out of a bathtub while being seated on a backrest tool by providing a tilt wall and a nearly vertical backrest wall face to face to form the bathtub backrest tool.

CONSTITUTION: A tilt wall 11 having nearly the same width as that of a bathtub 3 and the inclination along the backrest section 32 of the bathtub 3 and a nearly vertical backrest wall 12 having nearly the same height as the depth of the bathtub 3 are provided face to face to form a bathtub backrest tool 1 made of a soft polyurethane foam, and a nearly recessed spherical recess section 13 is provided at the center upper end of the backrest wall 12. An edge rod-like iron spindle 2 is nearly horizontally buried in the bathtub backrest tool 1 so that the axial direction coincides with the width direction of the backrest tool 1, and the whole surface is covered with a film made of an independent bubble cross-linking polyethylene foam body. The backrest tool 1 is inserted in the bathtub 3 so that the tilt wall 11 is kept in contact with the backrest section 32.