PURPOSE: To obtain a quantitative stop coil easy to handle and having a high reliability without requiring many mechanical rotation parts by composing it of a pushbutton, a flow detecting means, an accumulation circuit, a quantity setting means, an excitation circuit, and an electromagnet.

CONSTITUTION: When a pushbutton 6 is pushed, a ball 3a is pushed, and a valve 3 is opened to discharge water. A lock mechanism 8 is composed of an engagement part 6a and a plunger 7a to engage the lower end of the plunger 7a with the engagement part 6a for locking the pushbutton 6 at this time. A flow detecting means 13 is composed of a turbine 4 and a DC power generator 12. During discharge of water, an electric energy in proportion to a flow is accumulated in the accumulation circuit 14 by the flow detecting means 13, and when a terminal voltage of a capacitor C1 reaches a predetermined value, a coil 7c is energized to move the plunger 7a up and release locking of the pushbutton 6. The pushbutton 6 is then moved right by a back string 9 to restore, and the ball 3a sets in contact with a valve seat 3b to close a valve 3 and stop discharge.