A range finding device comprising: a light projecting unit mounted on a moving body, having an irradiation domain extending in a horizontal direction, and configured to project intensity-modulated irradiation light; an image capturing unit mounted on the moving body, and configured to capture an image of an object irradiated with the irradiation light; a light projection controller configured to control an intensity of the irradiation light in accordance with a timing at which the image capturing unit captures the image; and a synchronous detection unit configured to extract a region in which brightness changes in synchronism with intensity modulation of the irradiation light, as a synchronous detection region, from the image captured by the image capturing unit ; characterized by an edge detector configured to detect an edge of the synchronous detection region; and a range calculator configured to calculate a distance to the object on the basis of the edge of the synchronous detection region detected by the edge detector , wherein if the change in the brightness of the image captured by the image capturing unit brings about a brightness output value in a non-linear region of the image capturing unit , the synchronous detection unit is configured to calculate an amplitude and a direct current component of the irradiation light which are needed to shift the change in the brightness of the image to a linear region of the image capturing unit , and the light projection controller is configured to control the intensity of the irradiation light on the basis of the calculated amplitude and direct current component of the irradiation light. a light projecting unit mounted on a moving body, having an irradiation domain extending in a horizontal direction, and configured to project intensity-modulated irradiation light; an image capturing unit mounted on the moving body, and configured to capture an image of an object irradiated with the irradiation light; a light projection controller configured to control an intensity of the irradiation light in accordance with a timing at which the image capturing unit captures the image; and a synchronous detection unit configured to extract a region in which brightness changes in synchronism with intensity modulation of the irradiation light, as a synchronous detection region, from the image captured by the image capturing unit ; characterized by an edge detector configured to detect an edge of the synchronous detection region; and a range calculator configured to calculate a distance to the object on the basis of the edge of the synchronous detection region detected by the edge detector , wherein if the change in the brightness of the image captured by the image capturing unit brings about a brightness output value in a non-linear region of the image capturing unit , the synchronous detection unit is configured to calculate an amplitude and a direct current component of the irradiation light which are needed to shift the change in the brightness of the image to a linear region of the image capturing unit , and the light projection controller is configured to control the intensity of the irradiation light on the basis of the calculated amplitude and direct current component of the irradiation light. <EOS>