A self-position calculating apparatus adapted to calculate a self-position of a vehicle comprising: a light projector configured to project a patterned light beam (32a, 32b) onto a road surface around the vehicle; an image capturing unit adapted to be installed in the vehicle, and configured to capture an image of the road surface around the vehicle including an area onto which the patterned light beam (32a, 32b) is projected; a patterned light beam extractor configured to extract a position of the patterned light beam (32a, 32b) from the image obtained with the image capturing unit; an orientation angle calculator configured to calculate an orientation angle of the vehicle relative to the road surface from the extracted position of the patterned light beam (32a, 32b); an orientation change amount calculator configured to calculate an amount of change in orientation of the vehicle based on temporal changes in a plurality of feature points (Te) on the road surface on the image obtained with the image capturing unit; and a self-position calculator configured to calculate a current position and a current orientation angle of the vehicle by adding the amount of change in the orientation to an initial position and an initial orientation angle of the vehicle, the initial orientation angle being calculated by the orientation angle calculator, wherein if a detected brightness condition of the patterned light beam (32a, 32b) is equal to or greater than a threshold value, the patterned light beam extractor generates a superimposed image by superimposing images in frames obtained with the image capturing unit, and extracts the position of the patterned light beam (32a, 32b) from the superimposed image. a light projector configured to project a patterned light beam (32a, 32b) onto a road surface around the vehicle; an image capturing unit adapted to be installed in the vehicle, and configured to capture an image of the road surface around the vehicle including an area onto which the patterned light beam (32a, 32b) is projected; a patterned light beam extractor configured to extract a position of the patterned light beam (32a, 32b) from the image obtained with the image capturing unit; an orientation angle calculator configured to calculate an orientation angle of the vehicle relative to the road surface from the extracted position of the patterned light beam (32a, 32b); an orientation change amount calculator configured to calculate an amount of change in orientation of the vehicle based on temporal changes in a plurality of feature points (Te) on the road surface on the image obtained with the image capturing unit; and a self-position calculator configured to calculate a current position and a current orientation angle of the vehicle by adding the amount of change in the orientation to an initial position and an initial orientation angle of the vehicle, the initial orientation angle being calculated by the orientation angle calculator, wherein if a detected brightness condition of the patterned light beam (32a, 32b) is equal to or greater than a threshold value, the patterned light beam extractor generates a superimposed image by superimposing images in frames obtained with the image capturing unit, and extracts the position of the patterned light beam (32a, 32b) from the superimposed image.