The electric brake actuator with a parking function is provided with: detection unit (35) 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 (39) configured to determine whether or not a locking mechanism (5) has shifted to a parking locking state, by using a detection signal outputted from the detection unit (35), when the locking mechanism (5) is driven by an actuator (30) so as to switch from an unlocking state to the parking locking state.