PURPOSE: To drastically reduce the discharge noise of fluid, obtain the high quality feeling, increase the pumping-up quantity and improve the performance of a pump by connecting a bypass flow passage which allows the fluid discharge port side of a pressure adjusting valve to communicate to a fluid discharge port.

CONSTITUTION: When the fluid on the main side is jetted from a nozzle 2b, a negative pressure is generated at the fluid discharge port 8a of a diffuser 8, and the fuel in a subtank ST is introduced into a subside fluid introducing passage 2c. The fluid is sucked into the fluid discharge port 8a through a subside fluid suction passage 8b, and the fluid on the main side and subside is discharged into a main tank MT from the fluid discharge port 8a. During this time, if the pressure of the fluid on the main side which is introduced into a main side fluid introducing passage 2a increases over a prescribed value, a valve body 4a is pressed against the elastic repulsive force of the spring 4b of a pressure adjusting valve 4, and the pressure adjusting valve 4 is put into an opened state, and the fluid on the main side is allowed to flow into a bypass flow passage 11. The fluid on the main side which flows out is discharged into the main tank MT, mixed with the fluid on the main side and subside at the fluid discharge port 8a.