To provide a residual lifetime display circuit which can display the residual lifetime of electronic parts.

This residual lifetime display circuit consists of an electronic device and management 8 which is connected to the electronic device via an interface 6 and manages the electronic parts of the electronic device. Then, the circuit is provided with a power switch 1 to control power supply to the electronic parts, a counter 2 which counts the time of the power supply to the electronic parts, a memory 4 which stores the operable time of the electronic parts, a display part 5 which displays the residual lifetime of the electronic parts and a control part 3 which controls those means. In such a constitution, the part 3 subtracts the count value sent from the counter 2 from the operable time stores in the memory 4 to display the residual lifetime of the electronic parts being the subtraction result and also to notify the external manager 8 of the residual lifetime. Thus, a user can easily know the replacement time of the electronic parts and also can perform the maintenance such as the parts replacement before the end of the lifetime of the electronic parts.