PURPOSE: To provide a drain valve controller which reduces the opening of the body of a drain valve to reduce noise caused by drainage from a drain pipe.

CONSTITUTION: The AC synchronous type small motor 5 of a motor actuator 3 which pulls a wire 4 for connection to the body 2 of a drain valve 1 has its rotation controlled by a drive controller (not shown in Figure). To reduce the displacement of the drain valve 1, rotation of the AC synchronous type small motor 5 is commanded by the drive controller for a shorter period than the time during which the valve body 2 is full open, so that the opening of the valve body 2 is reduced.