In a vehicle, a vehicle body-side apparatus is configured to perform a main area determination and an auxiliary area determination. The main area determination determines whether a portable terminal is present in a main area based on a first reception intensity measured by the vehicle body-side apparatus in a wireless signal from the portable terminal. The auxiliary area determination determines whether the portable terminal is present in an auxiliary area based on a second reception intensity measured by a vehicle tire-side apparatus in a wireless signal from the portable terminal.