A caliper body (12) of a disc brake apparatus (10) includes an accommodating portion (14a) which accommodates a piston (20) for pressing a brake pad (66), a cam lever (42) for generating a pressing force through rotation, and a pressing force transmission mechanism (24) which is interposed between the piston (20) and the cam lever (42) to transmit a pressing force to the piston (20). The accommodating portion (14a) has an opening portion through which the piston (20), the cam lever (42) and the pressing force transmission mechanism (24) can be assembled into the caliper body (12) from a thick back side thereof, and both the accommodating portion (14a) and the opening portion are opened to a rotor disposition side area in the caliper body (12).