To provide a vehicle monitoring device of a vehicle with a smart key system and a TPMS which control not to cause radio wave interference of a transmission from a keyless unit with a transmission from a TPMS sensor started automatically at the TPMS after IG ON.

While initial checking of each TPMS sensor 21 by a TPMS-ECU 15 of the TPMS just after IG ON, in the case when a smart key ECU 16 becomes a necessary condition for the communication with the keyless unit 18, after the control of processing TPMS sensor 21 is ended, the TPMS-ECU 15 once interrupts the initial checking of the residual TPMS sensor 21. The smart key ECU 16 makes a communication to determine that the keyless unit 18 is present in a vehicle interior, and after that, the TPMS-ECU 15 restarts the initial checking of the residual TPMS sensor 21. Accordingly, the TPMS-ECU 15 and the smart key ECU 16 make timing adjustment with a CAN communication line 17.