A motor driven brake apparatus is provided for braking a wheel mounted on a knuckle, and includes a brake member rotated integrally with the wheel, a friction member mounted on the knuckle to be capable of being in contact with the brake member, and an electric motor for driving the friction member toward the brake member to be in contact therewith. The motor is adapted to press the friction member onto the brake member to restrain the wheel from rotating. And, a motion converter is accommodated in an opening portion of the knuckle for converting rotating force of the motor into pressing force applied by the friction member onto the brake member. The motion converter is connected to the motor at a side thereof facing the vehicle body, and the motor is mounted on the knuckle.