An image sensor mounting base includes a substrate, and a first, a second, a third and a fourth electrode pad. The substrate has an upper surface including a first mount area where a first image sensor is mountable, and a second mount area where a second image sensor is mountable. The second mount area is spaced from the first mount area. The first and second electrode pads are located on the upper surface of the substrate and across the first mount area each other. The third and fourth electrode pads on the upper surface of the substrate are spaced from the first electrode pad and the second electrode pad and face each other across the second mount area. The substrate has, on the upper surface, a recess between the third electrode pad and the fourth electrode pad. The second mount area is located on a bottom of the recess.