A disc brake enables a parking apparatus to be operated via actuation of an electric motor, thereby permitting easy operation of the parking apparatus. The disc brake comprises a piston to compress a friction pad used for braking of a disc, a caliper housing to receive the piston such that the piston moves linearly therein, and having a cylinder section to which a hydraulic pressure for braking is applied, an actuation shaft rotatably installed within the cylinder section, and having a male screw formed thereon, a compression sleeve installed within the piston to compress or release the piston while linearly moving therein by rotation of the actuation shaft, and having a female screw formed thereon to engage with the male screw of the actuation shaft, an electric motor to rotate the actuation shaft, a multi-stage reduction gear train to transmit rotational force of the electric motor to the actuation shaft. The multi-stage reduction gear train has a central axis deviated from that of the electric motor, and a shaft connected with a shaft of the electric motor via a power transmission unit.