A remote diagnostic system of a mold handling device provided with a clamp for mounting at least two kinds of state detection switches among a state detection switch for detecting an advance position for detecting whether it is close to a mold (M1, M2), a state detection switch for detecting a retreat position for detecting whether it is separated from the mold (M1, M2) to a limit position, a state detection switch for detecting that an output member of a clamp device has locked the mold (M1, M2), a state detection switch for detecting whether the output member has released the mold (M1, M2), a state detection switch for detecting whether a hydraulic pressure for locking a clamp rod exceeds a threshold value, and a state detection switch for detecting whether the hydraulic pressure for releasing the clamp rod exceeds a threshold value, wherein the remote diagnostic system comprises: a control unit, comprising: a main body side memory for storing an ON/OFF state of the state detection switch mounted on the clamp device together with information as to whether or not a mold handling device main body is in a mold replacement mode (a status of the main body), information as to whether the clamp device is in a clamped state or an unclamped state or other states (clamping status), and time information; and a main body side communication unit capable of short range wireless communication or wired communication; and a terminal device, comprising: a terminal side memory for storing messages for diagnosing failures for all the combinations in the ON/OFF state of the state detection switch mounted on the clamp device as to each case whether or not the mold handling device main body is in a mold replacement mode, whether the clamp device is in a clamped state or an unclamped state or other states; a terminal side communication unit reading histories of the ON/OFF states of the state switch to the main body status and the clamping status from the main body side memory by the wireless communication or the wired communication; and a display unit for obtaining and displaying messages corresponding to the read histories from a portable side memory. a control unit, comprising: a main body side memory for storing an ON/OFF state of the state detection switch mounted on the clamp device together with information as to whether or not a mold handling device main body is in a mold replacement mode (a status of the main body), information as to whether the clamp device is in a clamped state or an unclamped state or other states (clamping status), and time information; and a main body side communication unit capable of short range wireless communication or wired communication; and a main body side memory for storing an ON/OFF state of the state detection switch mounted on the clamp device together with information as to whether or not a mold handling device main body is in a mold replacement mode (a status of the main body), information as to whether the clamp device is in a clamped state or an unclamped state or other states (clamping status), and time information; and a main body side communication unit capable of short range wireless communication or wired communication; and a terminal device, comprising: a terminal side memory for storing messages for diagnosing failures for all the combinations in the ON/OFF state of the state detection switch mounted on the clamp device as to each case whether or not the mold handling device main body is in a mold replacement mode, whether the clamp device is in a clamped state or an unclamped state or other states; a terminal side communication unit reading histories of the ON/OFF states of the state switch to the main body status and the clamping status from the main body side memory by the wireless communication or the wired communication; and a display unit for obtaining and displaying messages corresponding to the read histories from a portable side memory. a terminal side memory for storing messages for diagnosing failures for all the combinations in the ON/OFF state of the state detection switch mounted on the clamp device as to each case whether or not the mold handling device main body is in a mold replacement mode, whether the clamp device is in a clamped state or an unclamped state or other states; a terminal side communication unit reading histories of the ON/OFF states of the state switch to the main body status and the clamping status from the main body side memory by the wireless communication or the wired communication; and a display unit for obtaining and displaying messages corresponding to the read histories from a portable side memory.