A parking assist system for use in a parking lot including parking spaces for a plurality of vehicles includes: a vehicle sensor which determines whether an assisted vehicle attempting to enter or exit one of the parking spaces is a general vehicle that travels through vehicle operation by a driver or an autonomous vehicle capable of self-driving according to an external travel signal; and a travel signal transmitter which, when the assisted vehicle is determined as the general vehicle, transmits, to a specific autonomous vehicle among parked autonomous vehicles, a travel signal for traveling to an available position for enabling the entry or the exit of the assisted vehicle.