A supporting structure is mounted on a hand body facing a circumferential edge of a substrate from below the substrate to support the substrate. First and second guiding members are mounted on the hand body, and having guiding surfaces in contact with an imaginary cylinder having an axis aligned with a reference axis of the hand body. First and second movable members are capable of moving in an imaginary plane perpendicular to the reference axis and are disposed on the radially outer-side of the circumferential edge of the substrate so as to face the circumferential edge. A driving unit simultaneously displaces the first and second movable members in the imaginary plane. The first and second guiding members and the first and second movable members are spaced apart on the circumference of the imaginary cylinder at intervals greater than the length of the arc of a segment in a substrate holding state.