A fluid feed pump is configured, such that a fluid is fed from an outlet channel of the fluid feed pump through an outlet buffer chamber to a fluid channel. The outlet buffer chamber is designed to have a higher compliance than a compliance of a pump chamber. The driving period of the fluid feed pump is set to a shorter period than a time constant defined by the compliance of the pump chamber and a flow resistance between an inlet of the outlet channel and an outlet of the fluid channel. This enables the fluid to be fed with high efficiency by taking advantage of the pressure oscillation occurring between the pump chamber and the outlet buffer chamber.