To provide an electric parking brake system reduced in power consumption by controlling tension at a proper value to maintain a vehicle in the stop condition, considering the temperature and temperature characteristics of a sensor.

A forward/backward acceleration sensor has a characteristic that an absolute value of an error becomes smaller in the case wherein the temperature is higher than a standard temperature T in comparison with a lower case. In the case of not considering the temperature characteristic, an absolute value of an error is assumed to be the maximum value d independently of the temperature, and forward/backward acceleration is obtained, and a tilt angle is obtained. On the other hand, in the case of considering the temperature and temperature characteristics, an absolute value c (cd) of an error can be obtained when the temperature is higher than the standard temperature T. As a result, a tilt angle close to a real value can be obtained based on a detection value of the forward/backward acceleration sensor. A smaller target value proper to maintain the vehicle in the stop condition can be thereby obtained to reduce the power consumption.