PURPOSE: To facilitate the water cleaning of a bath boiler by a method wherein a connecting tube piece is protruded at the rear part of an elastic cover piece having a frontal opening, the size of which is large enough to cover the circulating port of a bathtub connecting the bath heater therethrough, so as to couple the hose of a pump.

CONSTITUTION: The titled washing tool of a bath boiler consists of a cover utensil with a connecting tube piece 49 protruded at the rear end of an elastic cover piece 48 having a frontal opening, the size of which is large enough to cover the circulating port of a bathtub connecting the bath heater therethrough. The hose 46 of a pump is connected to the connecting tube piece 49. Accordingly, even when the hose of the pump can not be inserted in the circulating port, the cleaning of the interior of the bath boiler can be performed easily.