A smart key carried with a user is provided with switches for monitoring a vehicle in remote places, such as a departure-time monitor switch, a return-time monitor switch and an all item monitor switch. The switches are associated with monitor information indicating various vehicle states. When the departure-time monitor switch is operated, the cellular phone receives monitor information such as parking position, rainfall state, etc. useful to the user at departure time from the vehicle. Similarly, when the return-time monitor switch is operated, the cellular phone receives monitor information useful at return time such as door open/closed state and lock state. When the all item monitor switch is operated, the cellular phone receives monitor information of all monitor items.