To provide a vehicular communication control system which carries out control based on communication between a portable machine and an on-vehicle device, with good accuracy.

According to the system, the portable machine 10 detects a receiving level when a request signal is received, and transmits an ID code signal inclusive of a receiving level code indicative of the receiving level. The on-vehicle device 20 is formed of: an in-vehicle transmission circuit 22 for transmitting the request signal into a cabin of a vehicle; an ID receiving circuit 25 for receiving the ID code signal: a request receiving circuit 24 configured so as to receive the request signal transmitted to the cabin of the vehicle, and having a transmitting/receiving antenna 27 arranged at a request signal transmission critical location in the vehicle 2; and a vehicle control section 21 for allowing engine start only when the receiving level of the request signal by the request receiving circuit 24 is equal to or higher than the receiving level included in the ID code signal.

COPYRIGHT: (C)2007,JPO&INPIT