A heat treatment apparatus, comprising: a heating unit (2, 102), which is configured to inductively heat a ring-shaped workpiece to a target temperature; and a drive mechanism, which is configured to move a plurality of the coaxially held ring-shaped workpieces in a stacked state in which the ring-shaped workpieces are stacked in multiple levels relative to the heating unit (2, 102) being in an energized state in an axial direction of the ring-shaped workpiece, characterized in that the heating unit (2, 102) comprises: a plurality of coil members (11, 111) arranged in multiple levels along the axial direction of the ring-shaped workpiece, wherein each of the plurality of coil members (11, 111) comprises a coil portion (11a, 111a) which is arranged coaxially with the ring-shaped workpiece so as to be capable of surrounding the ring-shaped workpiece, and each parts of the coil portion (11a, 111a) in an extending direction of the coil portion (11a, 111a) are positioned on the same plane; a frame body (21, 121), which is configured to support each of the plurality of coil members (11, 111) so as to be movable in the axial direction of the ring-shaped workpiece while maintaining the coaxial arrangement between the coil portions (11a, 111a); and a connecting component formed of a metal material having conductivity, wherein each of the plurality of coil members (11, 111) is supported on the frame body (21, 121) through a support component (22, 122) which is provided at the coil portion (11a, 111a) while being in a horizontal posture in which a center of axis of the coil portion (11a, 111a) thereof matches a center of axis of the coil portion (11a, 111a) of the another coil member (11, 111), wherein the support component (22, 122) is provided so as to be able to movable in the axial direction of the ring-shaped workpiece relative to the frame body (21, 121), and wherein the connecting component is configured to electrically connect two of the plurality of coil members (11, 111) being adjacent to each other in the axial direction of the ring-shaped workpiece. a heating unit (2, 102), which is configured to inductively heat a ring-shaped workpiece to a target temperature; and a drive mechanism, which is configured to move a plurality of the coaxially held ring-shaped workpieces in a stacked state in which the ring-shaped workpieces are stacked in multiple levels relative to the heating unit (2, 102) being in an energized state in an axial direction of the ring-shaped workpiece, characterized in that the heating unit (2, 102) comprises: a plurality of coil members (11, 111) arranged in multiple levels along the axial direction of the ring-shaped workpiece, wherein each of the plurality of coil members (11, 111) comprises a coil portion (11a, 111a) which is arranged coaxially with the ring-shaped workpiece so as to be capable of surrounding the ring-shaped workpiece, and each parts of the coil portion (11a, 111a) in an extending direction of the coil portion (11a, 111a) are positioned on the same plane; a frame body (21, 121), which is configured to support each of the plurality of coil members (11, 111) so as to be movable in the axial direction of the ring-shaped workpiece while maintaining the coaxial arrangement between the coil portions (11a, 111a); and a connecting component formed of a metal material having conductivity, a plurality of coil members (11, 111) arranged in multiple levels along the axial direction of the ring-shaped workpiece, wherein each of the plurality of coil members (11, 111) comprises a coil portion (11a, 111a) which is arranged coaxially with the ring-shaped workpiece so as to be capable of surrounding the ring-shaped workpiece, and each parts of the coil portion (11a, 111a) in an extending direction of the coil portion (11a, 111a) are positioned on the same plane; a frame body (21, 121), which is configured to support each of the plurality of coil members (11, 111) so as to be movable in the axial direction of the ring-shaped workpiece while maintaining the coaxial arrangement between the coil portions (11a, 111a); and a connecting component formed of a metal material having conductivity, wherein each of the plurality of coil members (11, 111) is supported on the frame body (21, 121) through a support component (22, 122) which is provided at the coil portion (11a, 111a) while being in a horizontal posture in which a center of axis of the coil portion (11a, 111a) thereof matches a center of axis of the coil portion (11a, 111a) of the another coil member (11, 111), wherein the support component (22, 122) is provided so as to be able to movable in the axial direction of the ring-shaped workpiece relative to the frame body (21, 121), and wherein the connecting component is configured to electrically connect two of the plurality of coil members (11, 111) being adjacent to each other in the axial direction of the ring-shaped workpiece.