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). <EOS>