A security sensor system is provided which allows the stopping of the device due to the end of a battery life to be postponed by suppressing battery power consumption, which is caused due to an object detection operation of the security sensor system, after a low battery state is detected. The security sensor system is powered by a battery. When a low battery detector detects a reduction in the voltage of the battery, an object detection operation of the security sensor system is switched from a normal mode to a suppression mode. Consumption of the battery in the suppression mode is suppressed.