PURPOSE: To make a flush valve lightly operable without having an effect on water pressure by operating a plunger opening and closing a flush valve by a movable magnet while working the magnet by a push-button through a release.

CONSTITUTION: When a user depresses an operating button 10, a magnet 14 is moved through a release 9, the magnet shifts a plunger 24 by magnetic force, a water conduit 2 is opened by the movement of the plunger 24, water in a water chamber 5 for a flush valve 1 is flowed out, and wash water is flowed to the stool side. Water in the water chamber 5 for the flush valve 1 is extracted and the flush valve 1 is operated, sliding resistance is redeuced without being subject to the effect of water pressure, light operation is enabled while the magnet 14 is moved by its own weight, etc., when a user separates its hand from the button 10, magnetic force is eliminated, and the water conduit 2 is closed by the force of a spring. Accordingly, operationability can be improved.