A calibration method for calibrating an attitude of a camera mounted on a vehicle using markers each arranged vertically and each positioned at a pre-designated height from a road surface. The method includes: a first process including shooting an image of the markers with the camera, thereby generating a two-dimensional image; a second process including converting the two-dimensional image into a bird's eye view image on a specific plane so that the bird's eye view image reflects the height of each of the markers; and a third process including calculating a parameter of the camera based on a position difference between the markers in the specific plane obtained in the second process.