To obtain a bathtub for achieving a cost reduction, an easy model change, and an addition of bathtub bodies.

A flexible heat insulating material 12 is fixed to a bathtub body 11 so as to follow an outer peripheral shape of the bathtub body 11. Heat insulating material 12 is covered with a net 31, and the heat insulating material 12 and the net 31 are tightened by a tightening rope 33 for positioning and fixing the heat insulating material 12. Thereby, molding of the heat insulating material corresponding to a shape of the bathtub body 11 is not required, resulting in a cost reduction for manufacturing the bathtub 10, and also resulting in facilitation of a change of shapes or sizes of the bathtub bodies or addition of the bathtub bodies.