There is provided a suck back valve system in which problems in the suck back function are resolved. In a suck back system including an integral-type suck back valve in which an on/off valve that performs opening and closing operations by a first pneumatic actuator has a suck back function of preventing liquid dripping by means of a diaphragm that moves with the closing operation and a protective on/off valve provided at the upstream side adjacent to the integral-type suck back valve as a measure against malfunction in the integral-type suck back valve and performing opening and closing operations by a second pneumatic actuator, an opening and closing control unit is provided that, during the fully closing operation of the integral-type suck back valve, completes the fully closing operation of the protective on/off valve earlier than full closing of the integral-type suck back valve.