To reduce a bad influence on a tracking control signal and a data signal by reflected light from an adjacent layer on a multi-layer disc as stray light, the following device is made in the invention. Reflected light from the multi-layer optical disc including stray light from another layer is once converged by a reflected light condenser lens and is reflected on a reflector. A grating which prevents zero-order light from being generated by setting groove depth to λ/4 and which is set to pitch to prevent positive and negative first- or higher-order diffracted lights from returning to the reflected light condenser lens is arranged between the lens and the reflector including an optical axis with the grating apart from the reflector. Hereby, as reflected light from another layer is cut off though reflected light from a corresponding layer is transmitted to a detector, a detected control signal and a detected data signal are not influenced by reflected light from another layer.