An apparatus for calibrating a camera comprises a camera; an input unit configured to receive a segmentation diagonal ratio of the environment quadrangle; a memory configured to store a program; and a processor configured to perform camera calibration based on the program, wherein the program is configured to: extract diagonal parameters of a centered quadrangle from the image; estimate length of a projection center line; estimate a projection angle; estimate an angle between diagonals of a projection quadrangle; estimate a projection center point; and estimate extrinsic and intrinsic parameters of the camera.