The invention improves performance of a solid-state image sensor in which each of the pixels arranged in a pixel array part includes a microlens and plural photodiodes. The locations of the opposing sides between the photodiodes arranged side by side in each pixel are self-alignedly defined by a gate pattern. The location over wiring where the microlens is to be formed is checked and determined using as a superposition mark a check pattern of the same layer as a gate layer.