PURPOSE: To restrain deterioration in lubricating ability due to temperature rise of fuel and eliminate a bad effect on a fuel injection quantity.

CONSTITUTION: The opening part of the inner pressure chamber 21 in the pump housing 13 of a fuel injection pump 1 is communicated to the way of a feed pump introducing passage 39 through a communicating passage 52, and a regulating valve 56 is arranged on the way of the passage 52. When the fuel pressure in the inner pressure chamber 21 is increased to be over prescribed pressure, the regulating valve 56 is opened, surplus fuel in the inner pressure chamber is let flow from the lower stream side into the feed pump introducing passage 39 through the communicating passage 52, and the fuel is introduced again to a fuel feed pump from the feed pump introducing passage 30. Consequently, abnormal pressure rise in the inner pressure chamber 21 is previously prevented. All the discharged and fed fuel accompanying rotation of the fuel feed pump is once let flow in the inner pressure chamber 21 through a feed passage 20, and hence temperature rise in the inner pressure chamber 21 due to decrease of flow is restrained.