The electric brake actuator with a parking function is provided with: detection unit which is provided in a vehicle in which the electric brake actuator is provided and is capable of detecting movement of the vehicle from a stop state; and determination unit configured to determine whether or not a locking mechanism has shifted to a parking locking state, by using a detection signal outputted from the detection unit, when the locking mechanism is driven by an actuator so as to switch from an unlocking state to the parking locking state.