A heat-treatment device (10, 100, 200) comprising: a table on which a ring-shaped workpiece can be placed; and a pair of heat processing units (20a, 20b) configured to heat-process a peripheral surface of the workpiece, the pair of heat processing units (20a, 20b) heat-processing the workpiece while moving in opposite directions along the peripheral surface of the workpiece in order to obtain the workpiece having desired properties, the heat-treatment device (10, 100, 200) further comprising: a pair of revolving arms (30a, 30b) configured to be movable relative to the table and to heat-process the peripheral surface of the workpiece by oscillating the pair of heat processing units (20a, 20b) relative to the workpiece, wherein the pair of heat processing units (20a, 20b) includes a pair of heating coils (21a, 21b) configured to be capable of being arranged to face the peripheral surface of the workpiece, and a pair of coolant discharge units (23a, 23b, 223a, 223b) configured to be disposed on the heating coils (21a, 21b) and to discharge a coolant, characterized in that the heat-treatment device (10, 100, 200) is adapted that the pair of heating coils (21a, 21b) sandwich the pair of coolant discharge units (23a, 23b) when the pair of heat processing units (20a, 20b) oscillate. a table on which a ring-shaped workpiece can be placed; and a pair of heat processing units (20a, 20b) configured to heat-process a peripheral surface of the workpiece, the pair of heat processing units (20a, 20b) heat-processing the workpiece while moving in opposite directions along the peripheral surface of the workpiece in order to obtain the workpiece having desired properties, the heat-treatment device (10, 100, 200) further comprising: a pair of revolving arms (30a, 30b) configured to be movable relative to the table and to heat-process the peripheral surface of the workpiece by oscillating the pair of heat processing units (20a, 20b) relative to the workpiece, wherein the pair of heat processing units (20a, 20b) includes a pair of heating coils (21a, 21b) configured to be capable of being arranged to face the peripheral surface of the workpiece, and a pair of coolant discharge units (23a, 23b, 223a, 223b) configured to be disposed on the heating coils (21a, 21b) and to discharge a coolant, characterized in that the heat-treatment device (10, 100, 200) is adapted that the pair of heating coils (21a, 21b) sandwich the pair of coolant discharge units (23a, 23b) when the pair of heat processing units (20a, 20b) oscillate. a pair of revolving arms (30a, 30b) configured to be movable relative to the table and to heat-process the peripheral surface of the workpiece by oscillating the pair of heat processing units (20a, 20b) relative to the workpiece, wherein the pair of heat processing units (20a, 20b) includes a pair of heating coils (21a, 21b) configured to be capable of being arranged to face the peripheral surface of the workpiece, and a pair of coolant discharge units (23a, 23b, 223a, 223b) configured to be disposed on the heating coils (21a, 21b) and to discharge a coolant, characterized in that the heat-treatment device (10, 100, 200) is adapted that the pair of heating coils (21a, 21b) sandwich the pair of coolant discharge units (23a, 23b) when the pair of heat processing units (20a, 20b) oscillate.