To provide a high pressure fuel pump having excellent responsiveness, and capable of following control with high accuracy.

This high pressure fuel pump comprises a discharge amount control valve 100 for feeding fuel discharged by reciprocally sliding a plunger 111 inserted in a pump chamber 110a by opening/closing a spill port 153a with a seat valve portion 150. A discharge amount control valve comprises a movable element portion 140a electromagnetically control the opening/closing of the spill port by the seat valve portion, a stem portion 140b for mediating an energizing force in the seat removing direction of the seat valve portion by a movable element portion, and a hollow portion 140c formed on at least either one of the seat valve portion, the movable element portion and the stem portion, and sealing gas inside thereof.