To eliminate the problems of a bath mat having a constitution wherein a reheating forward pipe is branched by a three-way valve and the branched side thereof is connected to a hot water inlet of the bath mat, while a hot water outlet of the mat is connected to the part of the hot water forward pipe on the downstream side of the three-way valve and hot water is circulated through the mat, that the mechanism of the mat is complicated and causes high cost, that it is difficult to disconnect the mat from the reheating forward pipe and so the mat can not be moved simply to be put away when it is not used and further that large work such as piping work is needed when the equipment mentioned above is added to a bathroom already provided.

In the case when a circulation metal fitting 4 having a hot water outlet is provided in a bathtub BT, an adapter 3 is fitted removably to the metal fitting 4 and the hot water discharged from the hot water outlet is circulated through the main body 1 of the mat.