A heat treatment device 1 comprising a heating unit 2 that inductively heats a region requiring quenching on a workpiece W to a target temperature, and a cooling unit 3 that cools and quenches the region requiring quenching on the workpiece W. A heat treatment end position P1 for the heating unit 2 and a cooling treatment start position P2 for the cooling unit 3 are positioned outside on one end and outside on the other end, respectively, of a workpiece passage A extending in the horizontal direction. The heat treatment device 1 comprises a transport device 50 that transports the workpiece W that has been obtained at the heat treatment end position P1 to the cooling treatment start position P2 in a state in which the workpiece W is not in contact with the defining surface of the workpiece passage A.