A parking assistance apparatus for a vehicle, and including a camera configured to photograph surroundings of the vehicle; an interface configured to receive sensor information from the vehicle; a display configured to display a graphic image about an automatic parking function of the vehicle; and a processor configured to initiate the automatic parking function by controlling the vehicle to travel to a target parking position, detect a traveling resistance of the vehicle from the sensor information while the vehicle is traveling to the target parking position, determine a factor causing the traveling resistance, continue controlling the vehicle to travel to the target parking position when the detected traveling resistance is less than a predetermined resistance, and change the controlling of the vehicle to travel to the target parking position to offset the factor causing the traveling resistance, when the detected traveling resistance is equal to or greater than the predetermined resistance.