A conductor connecting structure comprising: a first conductor having a flat plate terminal portion; a second conductor having a flat plate terminal portion (41a, 42a); a support having a recessed portion; a first screw member accommodated in the recessed portion; and a second screw member that co-fastens the terminal portion of the first conductor and the terminal portion (41a, 42a) of the second conductor by screwing to the first screw member, wherein the recessed portion has a first wall surface and a second wall surface that face each other in an opposing direction, and restricting surfaces (13a, 14a) that connect the first wall surface and the second wall surface along the opposing direction and restrict rotation of the first screw member, the first wall surface and the second wall surface form a retaining portion, located at a bottom of the recessed portion, configured to retain the first screw member before being screwed to the second screw member, and characterized by an allowable portion located closer to an inlet of the recessed portion than the retaining portion in a third direction, the third direction being a moving direction of the first screw member screwed to the second screw member, and a distance between the first wall surface and the second wall surface in the allowable portion is greater than a distance between the first wall surface and the second wall surface in the retaining portion, wherein the recessed portion has a third wall surface and a fourth wall surface that face each other and connect the first wall surface and the second wall surface along the opposing direction respectively, and each of the third and the fourth wall surfaces restricts the rotation of the first screw member as the restricting surfaces (13a, 14a). a first conductor having a flat plate terminal portion; a second conductor having a flat plate terminal portion (41a, 42a); a support having a recessed portion; a first screw member accommodated in the recessed portion; and a second screw member that co-fastens the terminal portion of the first conductor and the terminal portion (41a, 42a) of the second conductor by screwing to the first screw member, wherein the recessed portion has a first wall surface and a second wall surface that face each other in an opposing direction, and restricting surfaces (13a, 14a) that connect the first wall surface and the second wall surface along the opposing direction and restrict rotation of the first screw member, the first wall surface and the second wall surface form a retaining portion, located at a bottom of the recessed portion, configured to retain the first screw member before being screwed to the second screw member, and characterized by an allowable portion located closer to an inlet of the recessed portion than the retaining portion in a third direction, the third direction being a moving direction of the first screw member screwed to the second screw member, and a distance between the first wall surface and the second wall surface in the allowable portion is greater than a distance between the first wall surface and the second wall surface in the retaining portion, wherein the recessed portion has a third wall surface and a fourth wall surface that face each other and connect the first wall surface and the second wall surface along the opposing direction respectively, and each of the third and the fourth wall surfaces restricts the rotation of the first screw member as the restricting surfaces (13a, 14a).