1. A parking guide apparatus for vehicles, comprising: a camera mounted on a rear of a vehicle; a display unit disposed inside the vehicle; and a parking guide control unit connected to the camera and the display unit, the parking guide control unit comprises a parking logic operation unit receiving a steering angle, a speed, or a parking mode from the vehicle to perform a parking logic operation; a parking area guideline display unit displaying a parking area guideline for parking guide on the basis of the result of the logic operation of the parking logic operation unit; and an image synthesizer synthesizing the results, displayed by the parking logic operation unit and the parking area guideline display unit, and an image obtained by the camera, and the display unit displays the image synthesized by the image synthesizer, wherein the parking area guideline comprises a minimum width and maximum width of a parking-enabled area that are calculated by the parking area guideline display unit on the basis of dimensions of the vehicle and ambient landform information.