PURPOSE: To prevent the erroneous function of a switch for pump, by making contactless except said switch and improving the response of switching.

CONSTITUTION: Upon reduction of usage of water, the pressure in a pressure tank T will rise and upon reaching to the stopping pressure P2 of pump a pressure switch PS will open. Consequently a photocoupler Ftrl is broken. After elapsing the setting time, a transistor Tr is disabled to miss the trigger signal of the gate G of a triac SCR to disable it. Consequently an electromagnetic switch M for motor is released to stop the pump P. Since all except said switch M and a thermal relay Th are made contactless, the response of switching is improved.