A parking assist system, the system comprising: a camera unit configured to detect front view image or rear view image of a vehicle; a display unit configured to display the front view image or the rear view image of the vehicle; and a steering angle sensor configured to detect a steering angle of the vehicle, the system characterized by a processor unit configured to: recognize parking attempt from a transmission lever of a vehicle or manual input by the driver; generate a first parking guide line and a second parking guide line; detect a parking target area using the front or rear view image of the vehicle obtained by the camera unit to generate an imaginary parking line, and two reference points (15, 16) on the imaginary parking line; and determine whether the first parking guide line and the second parking guide line correspond to the imaginary parking line, an overlay unit configured to overlay the parking guide lines, the imaginary parking line and an estimated travel trajectory line on the front or rear view image of the vehicle, wherein a criterion of corresponding is whether an angle between the imaginary parking line and the first and second parking guide lines corresponds to a predetermined range, whether an intersection between the first and second parking guide lines and the second reference point on the imaginary parking line correspond to each other, or whether the intersection and an x coordinate of the second reference point correspond to each other, if the angle corresponds to a predetermined range, or the intersection and the reference point are matched, the processor unit generates the estimated travel trajectory line, and display the estimated travel trajectory line on the display unit using the overlay unit, and if the angle fails to correspond to a predetermined range, the processor unit generates an indication or a message for vehicle movement guide, which may be displayed on the display unit. a camera unit configured to detect front view image or rear view image of a vehicle; a display unit configured to display the front view image or the rear view image of the vehicle; and a steering angle sensor configured to detect a steering angle of the vehicle, the system characterized by a processor unit configured to: recognize parking attempt from a transmission lever of a vehicle or manual input by the driver; generate a first parking guide line and a second parking guide line; detect a parking target area using the front or rear view image of the vehicle obtained by the camera unit to generate an imaginary parking line, and two reference points (15, 16) on the imaginary parking line; and determine whether the first parking guide line and the second parking guide line correspond to the imaginary parking line, an overlay unit configured to overlay the parking guide lines, the imaginary parking line and an estimated travel trajectory line on the front or rear view image of the vehicle, wherein a criterion of corresponding is whether an angle between the imaginary parking line and the first and second parking guide lines corresponds to a predetermined range, whether an intersection between the first and second parking guide lines and the second reference point on the imaginary parking line correspond to each other, or whether the intersection and an x coordinate of the second reference point correspond to each other, if the angle corresponds to a predetermined range, or the intersection and the reference point are matched, the processor unit generates the estimated travel trajectory line, and display the estimated travel trajectory line on the display unit using the overlay unit, and if the angle fails to correspond to a predetermined range, the processor unit generates an indication or a message for vehicle movement guide, which may be displayed on the display unit. recognize parking attempt from a transmission lever of a vehicle or manual input by the driver; generate a first parking guide line and a second parking guide line; detect a parking target area using the front or rear view image of the vehicle obtained by the camera unit to generate an imaginary parking line, and two reference points (15, 16) on the imaginary parking line; and determine whether the first parking guide line and the second parking guide line correspond to the imaginary parking line, an overlay unit configured to overlay the parking guide lines, the imaginary parking line and an estimated travel trajectory line on the front or rear view image of the vehicle, wherein a criterion of corresponding is whether an angle between the imaginary parking line and the first and second parking guide lines corresponds to a predetermined range, whether an intersection between the first and second parking guide lines and the second reference point on the imaginary parking line correspond to each other, or whether the intersection and an x coordinate of the second reference point correspond to each other, if the angle corresponds to a predetermined range, or the intersection and the reference point are matched, the processor unit generates the estimated travel trajectory line, and display the estimated travel trajectory line on the display unit using the overlay unit, and if the angle fails to correspond to a predetermined range, the processor unit generates an indication or a message for vehicle movement guide, which may be displayed on the display unit.