The invention relates to a simple, compact, and economical motor/pump unit (1) for supplying vacuum to a pneumatic brake booster of a motor-vehicle brake system, wherein the motor/pump unit (1) is designed as a diaphragm pump having a single elastomeric diaphragm (2), which is moved by an electrically operated motor unit (3) by means of an eccentric drive (4), and has a pump housing (5) and a working-space cover (6) and the diaphragm (2) is clamped between the pump housing (5) and the working-space cover (6) at the radial outer edge of the diaphragm in a sealing manner and the working-space cover (6) is designed as a multi-part working-space cover having an upper cover (8), a lower cover (9), and an inlet valve (10) and an outlet valve (11), which are arranged between the upper cover (8) and the lower cover (9) and control the air circulation through the working space (7).