A light-emitting-and-receiving element module comprising: a substrate that comprises a top surface ; a light-emitting element on the top surface of the substrate ; a light-receiving element on the top surface of the substrate and apart from the light-emitting element ; and an intermediate wall between the light-emitting element and the light-receiving element , the intermediate wall comprising a lower surface disposed apart from the top surface , wherein the lower surface of the intermediate wall has a protruding shape; characterized in that : the lower surface having the protruding shape is provided by a first inclined surface that faces the light-emitting element and a second inclined surface (5c2) that faces the light-receiving element and intersects the first inclined surface at an apex; light exiting from the light-emitting element in a direction away from the substrate can escape at the apex to the other side of the intermediate wall ; the first inclined surface is adapted to reflect light exiting from the light-emitting element to a region where the light-receiving element is not disposed; and the second inclined surface (5c2) is adapted so that the light exiting from the light-emitting element and escaping to the other side of the intermediate wall does not collide with the second inclined surface (5c2). a substrate that comprises a top surface ; a light-emitting element on the top surface of the substrate ; a light-receiving element on the top surface of the substrate and apart from the light-emitting element ; and an intermediate wall between the light-emitting element and the light-receiving element , the intermediate wall comprising a lower surface disposed apart from the top surface , wherein the lower surface of the intermediate wall has a protruding shape; characterized in that : the lower surface having the protruding shape is provided by a first inclined surface that faces the light-emitting element and a second inclined surface (5c2) that faces the light-receiving element and intersects the first inclined surface at an apex; light exiting from the light-emitting element in a direction away from the substrate can escape at the apex to the other side of the intermediate wall ; the first inclined surface is adapted to reflect light exiting from the light-emitting element to a region where the light-receiving element is not disposed; and the second inclined surface (5c2) is adapted so that the light exiting from the light-emitting element and escaping to the other side of the intermediate wall does not collide with the second inclined surface (5c2). the lower surface having the protruding shape is provided by a first inclined surface that faces the light-emitting element and a second inclined surface (5c2) that faces the light-receiving element and intersects the first inclined surface at an apex; light exiting from the light-emitting element in a direction away from the substrate can escape at the apex to the other side of the intermediate wall ; the first inclined surface is adapted to reflect light exiting from the light-emitting element to a region where the light-receiving element is not disposed; and the second inclined surface (5c2) is adapted so that the light exiting from the light-emitting element and escaping to the other side of the intermediate wall does not collide with the second inclined surface (5c2). <EOS>