PURPOSE: To exhaust vapor generated in great quantities at stopping a pump.

CONSTITUTION: By rotation of an impeller arranged in a pump chamber, pressure of fuel passing through the fuel flow passage 12a of the pump chamber is raised. The fuel flow passage 12a is formed with a first vapor exhaust hole (vapor exhaust hole at driving the pump) 20 on the position on which fuel pressure is raised to some extent. A second vapor exhaust hole (vapor exhaust hole at stopping the pump) 21 of larger passage area than that of the first vapor exhaust hole 20 is formed on the position on a little lower stream side of the opening of a suction passage 15. Namely, the second vapor exhaust hole 21 is provided on the position which is in the positive pressure territory at driving the pump and hardly raised in pressure. The passage area of the second vapor exhaust hole 21 is set so that vapor can be exhausted by buoyance of the vapor.