An air-conditioning control system for a vehicle includes: an occupant sensing unit that determines whether or not there is an occupant inside the vehicle when a driver exits from the vehicle; a ventilation control unit that performs control to allow external air to be introduced into the vehicle, upon sensing that there is an occupant in the vehicle; and a temperature control unit that senses at least one of an interior temperature of the vehicle and an external temperature at the time of controlling ventilation. The system is configured to control heating or cooling based on the sensed interior temperature or the external temperature.