PURPOSE: To automatically carry out flushing by providing a device with a flushing water feed valve the opening of which is made variable, the detectors of the flow rate of flushing water and a human body, and with the control device of them, and thereby either adjusting the opening of the feed valve or closing the feed valve by the specified quantity of water based on signals from the aforesaid detectors.

CONSTITUTION: A flushing water feed pipe line 3 connected to a water supply source 4 is provided with a feed valve 5 operated by a motor valve the opening of which can be made variable by a motor M capable of being normally or reversely operated where a human body detecting signal from a human body detector 1 is inputted into a controller 2. And a flow rate sensor 6 is disposed at the downstream side of the valve 5 to detect the flow rate of flushing water discharge out of a discharge port 3a. The detected signal is then inputted into the controller 2, so that the switching and opening control of the feed valve 5 is assumed based on both of the signals from the human body detector 1 and the detected flow rate signals via a drive circuit 7. By this constitution, flushing water can thereby be economized.