A pump according to the present invention comprises the main pump body 12 including the casing 14 to which the fluid is supplied, and the input valve section 18, the pump section 16, and the output valve section 20 which are provided opposingly to the back surface of the casing 14, for selectively forming a flow passage on the back surface of the casing 14 in accordance with selective displacement action of the input valve section 18, the pump section 16, and the output valve section 20 in a direction to make approach or separation with respect to the back surface of the casing 14, wherein the fluid is controlled for its flow in accordance with the selective formation of the flow passage.
With the above arrangement, a pump can be of the compact and thin type, making it possible to increase the discharge amount (movement amount) of fluid.