A start of a vehicle is made to be capable of limited in compliance with a necessity. For example, in a case where an operation mode at a time point in which a “request” from an ECU was received is a start inhibition mode, a portable electronic key forms an “answer” including a “start inhibition information”, and transmits that “answer” to the ECU by a UHF. In this case, in an ECU side, the start of the vehicle is inhibited. In contrast to this, in a case where it is a start permission mode, an “answer” not including the “start inhibition information” is formed and transmitted to the ECU. In this case, in the ECU side, the start of the vehicle is permitted. That is, by the fact that an accelerator is stepped on and the like, the vehicle starts. The present invention can be applied to a passive entry system.