ACTUATOR AND ELECTROMECHANICAL DISC BRAKE HAVING THE SAME

Disclosed is an electromechanical disc brake. The electromechanical disc brake includes a piston slidably disposed in a cylinder of a caliper housing to press a pad plate, an actuator including a motor and a speed reduction device for reducing a rotation speed of the motor, an output conversion device for converting a rotational motion from the speed reduction device into a linear motion and imparting a thrust to move the piston, an elastic member for moving the output conversion device to the original position when releasing braking, and a clutch device for releasing a torque acting on the speed reduction device such that the output conversion device is moved to the original position by the elastic member when releasing the braking.