A supporting force inspection system comprising a plurality of heat transfer tubes of a steam generator, a vibration suppression member interposed between bend portions of the plurality of heat transfer tubes and a supporting force inspection device for inspecting a supporting force of the vibration suppression member, the supporting force inspection device comprising: an acceleration sensor (116, 118, 119) for detecting a vibration state of the bend portions; a sensor holding part disposed inside the heat transfer tube and configured to hold the acceleration sensor (116, 118, 119); and a vibration force generation part configured to generate a vibration force for vibrating the heat transfer tube from an inner surface side of the latter along a plane in which a curvature circle of the bend portion exists, wherein the vibration force generation part is configured to cooperate with the sensor holding part and apply from an inner surface side of the heat transfer tube a vibration force to vibrate the heat transfer tube along the plane in which the curvature circle exists, wherein the acceleration sensor (116, 118, 119) is configured to detect the vibration state of the bend portion in a state where the sensor holding part is engaged with an inner surface of the heat transfer tube, wherein the vibration force generation part is configured to generate the vibration force so that the vibration force changes with time, wherein the sensor holding part is configured to close an inside of the heat transfer tube in a state of being engaged with the inner surface of the heat transfer tube, and wherein the vibration force generation part is configured to apply a pressure to a liquid filling the inside of the heat transfer tube closed by the sensor holding part so that the pressure changes with time. an acceleration sensor (116, 118, 119) for detecting a vibration state of the bend portions; a sensor holding part disposed inside the heat transfer tube and configured to hold the acceleration sensor (116, 118, 119); and a vibration force generation part configured to generate a vibration force for vibrating the heat transfer tube from an inner surface side of the latter along a plane in which a curvature circle of the bend portion exists, wherein the vibration force generation part is configured to cooperate with the sensor holding part and apply from an inner surface side of the heat transfer tube a vibration force to vibrate the heat transfer tube along the plane in which the curvature circle exists, wherein the acceleration sensor (116, 118, 119) is configured to detect the vibration state of the bend portion in a state where the sensor holding part is engaged with an inner surface of the heat transfer tube, wherein the vibration force generation part is configured to generate the vibration force so that the vibration force changes with time, wherein the sensor holding part is configured to close an inside of the heat transfer tube in a state of being engaged with the inner surface of the heat transfer tube, and wherein the acceleration sensor (116, 118, 119) is configured to detect the vibration state of the bend portion in a state where the sensor holding part is engaged with an inner surface of the heat transfer tube, wherein the vibration force generation part is configured to generate the vibration force so that the vibration force changes with time, wherein the sensor holding part is configured to close an inside of the heat transfer tube in a state of being engaged with the inner surface of the heat transfer tube, and wherein the vibration force generation part is configured to apply a pressure to a liquid filling the inside of the heat transfer tube closed by the sensor holding part so that the pressure changes with time.