A surveillance camera system using a power line communication technique is provided, which can operate in the same way as in the case where the AC power is supplied, even when the AC power is not supplied. Provided with DC power source units respectively in a camera unit and a control recording unit, it is switched to a drive by the DC power source units when the AC power is cut, and simply transmits the information signals such as monitored images through the AC power line without superimposing them on the AC power. Therefore, under the condition that the AC power line between the camera unit and the control recording unit is physically connected, transfer of the information signals is possible and the same operation as in the period when the AC power is supplied is possible even when the AC power is not supplied.