To form a highly durable and highly compatible switching valve which is mounted in a fluid discharging chamber of a pump motor.

The switching valve 9 is constituted of a lip 9a, a valve element 9b, a ring-shaped thin-wall section 9c which is formed at the outer periphery of the valve element 9b and is thinner than the valve element 9b, and for performing the switching operation of the valve element 9b, and a middle section 9d which is formed at its outer periphery and provided at a wall-thickness section between the valve element 9b and the thin-wall section 9c. An inclined surface section 9e is formed at the thin-wall section 9c, and the valve element 9b is inclined to one side surface of the lip 9a.