A high pressure container system is equipped with an upstream side pressure sensor that measures an internal pressure of high pressure containers upstream of a pressure regulating valve, a plurality of downstream side pressure sensors that measure the pressure of the fluid downstream of the pressure regulating valve, and a control device. At a normal time of the downstream side pressure sensors, a control device monitors the internal pressure of the high pressure containers on the basis of the measured values of the downstream side pressure sensors, and at an abnormal time when any one of the downstream side pressure sensors is abnormal, the control device monitors the internal pressure of the high pressure containers on the basis of the measured values of the downstream side pressure sensors, and the measured value of the upstream side pressure sensor.