ELECTRIC-POWERED PARKING BRAKE DEVICE

An electric parking brake system includes an electric motor (M); a linear motion mechanism (A) that converts the rotational movement of a rotor shaft (12) of the electric motor (M) to a linear movement of a slide member (5) to operate a brake; a locking mechanism (40) that fixes a position of the slide member (5); a control device (50) that controls the electric motor (M) and the locking mechanism (40); a brake load estimation means (60) that estimates a brake force; and an electric parking brake operation instruction device (70) that is arbitrary operable. The control device (50) automatically executes a parking brake operation when a stop state of the vehicle is detected even if the electric parking brake operation instruction device (70) is not operated; where an automatically applied parking brake force (F 1 ) is set to a value smaller than a normal parking brake force (Fmax) at time of normal parking brake operation by the operation of the parking brake operation instruction device (70), and the application range of the parking brake operation is expanded.