A solenoid valve system (10, 10A to 10C) comprising: a control unit; a plurality of solenoid valve units that are arranged in a row with respect to the control unit, the plurality of solenoid valve units including solenoids configured to drive solenoid valves by supply of electric power from the control unit; and a driving power supply, wherein the control unit comprises a safety circuit connected to the driving power supply provided externally, a solenoid valve drive circuit having an input side connected to the safety circuit and an output side connected to the plurality of solenoid valve units, and a control circuit configured to control the safety circuit and the solenoid valve drive circuit, the safety circuit comprises a first switching portion (36, 38) configured to switch supply and shutoff of electric power from the driving power supply to the solenoid valve drive circuit, by being controlled by the control circuit and a safety control circuit configured to perform diagnostic testing of the control unit, the solenoid valve system further comprises: a single common line (42, 82) connected to one terminal of the driving power supply through the safety circuit, and extending to the plurality of solenoid valve units and connected to one end of each of the plurality of solenoids; and a plurality of power lines (44, 50, 84, 86) connected to another terminal of the driving power supply through the safety circuit and connected respectively to other ends of the plurality of solenoids, the solenoid valve drive circuit comprises a plurality of second switching portions provided respectively on the plurality of power lines and configured to switch supply and shutoff of electric power from the safety circuit to the plurality of solenoids, by being controlled by the control circuit, the first switching portion includes a first switch provided on the common line and a second switch provided between the another terminal of the driving power supply and the plurality of power lines, characterized in that the safety control circuit includes a first controller configured to turn on/off the first switch by being controlled by the control circuit, a first diagnosis circuit configured to diagnose a state of the common line when the first switch is turned on/off, a second controller configured to turn on/off the second switch by being controlled by the control circuit, and a second diagnosis circuit configured to diagnose a state of the plurality of power lines when the second switch is turned on/off. wherein the control unit comprises a safety circuit connected to the driving power supply provided externally, a solenoid valve drive circuit having an input side connected to the safety circuit and an output side connected to the plurality of solenoid valve units, and a control circuit configured to control the safety circuit and the solenoid valve drive circuit, the safety circuit comprises a first switching portion (36, 38) configured to switch supply and shutoff of electric power from the driving power supply to the solenoid valve drive circuit, by being controlled by the control circuit and a safety control circuit configured to perform diagnostic testing of the control unit, a first switching portion (36, 38) configured to switch supply and shutoff of electric power from the driving power supply to the solenoid valve drive circuit, by being controlled by the control circuit and a safety control circuit configured to perform diagnostic testing of the control unit, the solenoid valve system further comprises: a single common line (42, 82) connected to one terminal of the driving power supply through the safety circuit, and extending to the plurality of solenoid valve units and connected to one end of each of the plurality of solenoids; and a plurality of power lines (44, 50, 84, 86) connected to another terminal of the driving power supply through the safety circuit and connected respectively to other ends of the plurality of solenoids, a single common line (42, 82) connected to one terminal of the driving power supply through the safety circuit, and extending to the plurality of solenoid valve units and connected to one end of each of the plurality of solenoids; and a plurality of power lines (44, 50, 84, 86) connected to another terminal of the driving power supply through the safety circuit and connected respectively to other ends of the plurality of solenoids, the solenoid valve drive circuit comprises a plurality of second switching portions provided respectively on the plurality of power lines and configured to switch supply and shutoff of electric power from the safety circuit to the plurality of solenoids, by being controlled by the control circuit, the first switching portion includes a first switch provided on the common line and a second switch provided between the another terminal of the driving power supply and the plurality of power lines, characterized in that the safety control circuit includes a first controller configured to turn on/off the first switch by being controlled by the control circuit, a first diagnosis circuit configured to diagnose a state of the common line when the first switch is turned on/off, a second controller configured to turn on/off the second switch by being controlled by the control circuit, and a second diagnosis circuit configured to diagnose a state of the plurality of power lines when the second switch is turned on/off.