PURPOSE: To easily acquire the content of a rental meter without visit to an installation location of the rental meter.

CONSTITUTION: The device is provided with a timer 3 outputting a time-out signal when a prescribed time elapses, a rental meter read circuit 2 reading the content of a rental meter 4 and outputting information when the timer 3 outputs a time-out signal, and a diagnostic processor 1 content information of the rental meter 4 outputted from the read circuit to a public line network 7 through a MODEM 5. When a prescribed time elapses and the timer 3 outputs a time-out signal, the read circuit 2 reads the content of the rental meter 4 and the diagnostic processor 1 sends the information to the public line network 7 through the MODEM 5. Then a maintenance center 6 receives the content information of the rental meter 4 through a MODEM 8.