HIGH-PRESSURE FUEL PUMP DEVICE

A high-pressure fuel pump device of the invention includes a plunger-type high-pressure pump unit (31) configured to pressurize fuel as a plunger (43) thereof makes reciprocating motion, a diaphragm-type supply pump unit (33) configured to suck in fuel in a fuel tank (11) and supply the fuel to the high-pressure pump unit as a diaphragm (87) thereof oscillates in conjunction with the reciprocating motion of the plunger, and a fuel return unit (34) provided in the supply pump unit and configured to return, to the fuel tank, surplus fuel that is not sucked into the high-pressure pump unit.