A remote maintenance system is provided that can perform maintenance on a mobile object by manipulations from a remote location. If a malfunction occurs in a vehicle (4), an ECU of the vehicle (4) is connected to a communication server (3) at a dealer (7). Next, an engineer of a maker (6) starts a maintenance terminal (1) in response to notification from the dealer (7) to transmit a command for requesting a DTC to the communication server (3). The DTC request command is transmitted to the ECU via a data management server (5) and the communication server (3), and the ECU transmits the DTC toward the maintenance terminal (1). The DTC which has been transmitted from the vehicle (4) is input to the maintenance terminal (1) via the communication server (3) and the data management server (5) and is displayed on the maintenance terminal (1). The engineer of the maker (6) evaluates the condition of the vehicle (4) using the displayed DTC, and then provides appropriate instructions to a technician of the dealer (7) and performs maintenance on the vehicle (4) by manipulating the maintenance terminal (1) on his own initiative.