There is provided a further saving in power consumption which is achieved by establishing an optimal transition from an ordinary operation mode to a power consumption saving mode. A mode switching management part (11c) as a mode switching part, while a communication of a managing part (11a) as a communication part to a mobile terminal (20) is being established, maintains an ordinary operation mode and when the communication of the management part (11a) to the mobile terminal (20) terminates, switches from the ordinary operation mode to a power consumption saving mode before an elapse of a specified power consumption saving time period.