To further suppress power consumption while maintaining the reaction time required for system operation.

An auto-lock system 10 comprises a cellular phone 12 as electronic equipment and an unlock device 14 paired with the cellular phone. The unlock device 14 intermittently transmits an unlock signal containing an ID code of the cellular phone 12. Since the unlock signal is transmitted in any one data format of either a full data format or an abbreviated data format in every transmission timing, a transmission time is reduced as a whole relative to a case where the unlock signal is transmitted in the full data format at all the time, and power consumption can be suppressed low just by the reduced transmission time.

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