PURPOSE: To provide an automatic hot water feeder controller which is installed in a large bathtub to retain the optimum water level of the supplied water.

CONSTITUTION: A cylindrical body 1 provided with an appropriate number of holes 3 at the peripheral face is fixed on the bottom of a bathtub 12 and erected thereon, in the inside of the bathtub. And several float balls 2 are contained in series in the cylinder so as to be vertically movable. And further, an opening/closing valve 4 is attached to the upper part in the cylinder and a tube body is fitted at the lower end of the valve. A valve seat 9 is stuck to the front end thereof to oppositely position it against the float. A hot water feed pipe 10 is connected to the inlet side of the valve and also connected to a hot water feed valve 14 and a water feed valve at the other end thereof. The valve 4 is automatically closed by the contact of the float 2 rising in the cylinder in accordance with the rise of hot water level in the bathtub, with the valve seat 9, to retain the optimum water level in the bathtub 12.