A high-pressure fuel supply pump comprising: a pressurizing chamber; and a high pressure path; and an outlet valve structure; and a pressure relief valve structure, wherein a valve seat member (S, 8a, 200a) shared by the outlet valve structure and the pressure relief valve structure is provided between the pressurizing chamber and the high pressure path; wherein a pressure relief valve seat of the pressure relief valve structure is provided on the side of the pressurizing chamber of the valve seat member (S, 8a, 200a); wherein an outlet valve seat of the outlet valve structure is provided on the side of the high pressure path of the valve seat member (S, 8a, 200a); wherein a pressure relief valve of the pressure relief valve structure is provided on the side of the pressurizing chamber of the pressure relief valve seat; wherein an outlet valve of the outlet valve structure is provided on the downstream side of the outlet valve seat; wherein a relief path is provided in the valve seat member (S, 8a, 200a), one end of the relief path is connected with the pressurizing chamber, the other end of the relief path is connected with the high pressure path; wherein an outlet path is formed in the valve seat member (S, 8a, 200a), one end of the outlet path is connected with the high pressure path, the other end of the outlet path is connected with the pressurizing chamber; characterized in that a load of a relief valve spring of the pressure relief valve structure is adjusted according to installation depth of a pressure relief valve body of the pressure relief valve structure; wherein the pressure relief valve body is fixed to the valve seat member (S, 8a, 200a). a pressurizing chamber; and a high pressure path; and an outlet valve structure; and a pressure relief valve structure, wherein a valve seat member (S, 8a, 200a) shared by the outlet valve structure and the pressure relief valve structure is provided between the pressurizing chamber and the high pressure path; wherein a pressure relief valve seat of the pressure relief valve structure is provided on the side of the pressurizing chamber of the valve seat member (S, 8a, 200a); wherein an outlet valve seat of the outlet valve structure is provided on the side of the high pressure path of the valve seat member (S, 8a, 200a); wherein a pressure relief valve of the pressure relief valve structure is provided on the side of the pressurizing chamber of the pressure relief valve seat; wherein an outlet valve of the outlet valve structure is provided on the downstream side of the outlet valve seat; wherein a relief path is provided in the valve seat member (S, 8a, 200a), one end of the relief path is connected with the pressurizing chamber, the other end of the relief path is connected with the high pressure path; wherein an outlet path is formed in the valve seat member (S, 8a, 200a), one end of the outlet path is connected with the high pressure path, the other end of the outlet path is connected with the pressurizing chamber; characterized in that a load of a relief valve spring of the pressure relief valve structure is adjusted according to installation depth of a pressure relief valve body of the pressure relief valve structure; wherein the pressure relief valve body is fixed to the valve seat member (S, 8a, 200a).