To prevent contact failure of each contact point of a high frequency power switch and secure a good contact state for a long time, and realize small sizing of the switch itself.

This is a billet heater 1 that comprises a plurality of furnaces 1a, 1b and heats by induction heating the billet 5 carried into the furnaces. The furnaces are installed in a row on a furnace fitting base 14 enabling reciprocal movement in one direction by a pressing drive device 13, and the fixed contact members 21, 21, which are connected to a high frequency power supply device 3, are arranged fixedly at the positions where they are opposed to the furnaces by reciprocal movement. The movable contact members 22a, 22a; 22b, 22b, which are respectively connected to the furnace, are arranged at the positions on the furnace fitting base 14 capable of contacting the fixed contact members in an opposed state. A switch 2 is provided which, by the movement of the furnace fitting base 14, changes from one to the other of the furnaces the high frequency power source 3 through the fixed contact members and the movable contact members.