An electric linear motion actuator is provided which can set the clearance during normal braking operation of an electric brake system. The linear motion actuator includes a load sensor for detecting the magnitude of the load with which a friction pad is pressed against the brake disk, a temperature sensor for compensating for the influence of temperature on the load sensor, and an electronic control unit. The electronic control unit is adapted to calculate a target rotational angle from the position of the electric motor corresponding to the magnitude of the load detected by the load sensor to the position of the electric motor where the clearance is at a predetermined value, and control the electric motor to rotate the electric motor by the target rotational angle.