PURPOSE: To indirectly heat a workpiece having a surface to be processed with hot-air supplied from a hot-air generator to heat-process a member to be heated well.

CONSTITUTION: In a heater for heat-processing, a closed heating chamber 4a that is formed via a workpiece 3 having a to-be-processed surface 3a of a member W to be heated and a hot-air generator 7 are connected by a supply path U and a return path M to form a closed circulation system. The supply path U is opened in the opposite or intersecting direction at the back of the workpiece 3 so that the workpiece 3 is indirectly heated by hot-air supplied from the supply path U.