To be capable of obtaining diffuse light with a sufficient amount of light, which is not susceptible to the influence of scratches of a film along the length direction, and to be capable of constructing the apparatus in a small size and at a low cost, a
digital audio signal S track or P track is formed on the side of the film furtherest to the left of the left perforations or to the right of right perforations of a movie film, respectively. Light from an LED 51 is diffused by an elliptical diffuser 52, the
diffusion angle of which is greater along the width direction of the film than along the length direction thereof, and is radiated onto the P track (or the S track). Then, the
transmitted light which has passed through the P track (or the S track) is converged onto a
line sensor 43A as a result of passing through a lens 42A, and the light is photoelectrically converted by the
line sensor 43A, thereby reproducing digital sound.