To provide a dust-proofing member for a heat treatment furnace, which suffers from no peeling or chipping-off even after a long-term service and to provide a heat treatment furnace.

The dust-proofing member 5A for a heat treatment furnace is a dust-proofing member 5A disposed between the wall 2 of a heat treatment furnace 1 and a workpiece 7 and comprises a substrate 5Aa made of crystallized glass or a ceramic sintered compact and a heat-resistant film 5Ab formed on at least either of the substrate surface which faces toward the side of the workpiece 7 and the substrate surface which faces toward the side of the wall 2. The heat-resistant film 5Ab has a thickness of 10 nm to 10 m.