To facilitate roof material replacement working by providing a gripping part on the base end side of a long replacement plate part inserted between roof materials, and providing a wire saw blade so as to be housed within the plate thickness of the replacement plate part.

In the case where a part of roof material is roofed, the gripping part 2 of a cutting saw for roof material replacement is gripped to insert an insertion plate part 1 between the roof materials. The roof material is attached and nails and machine screws are cut by a wire saw blade 9 by gripping the gripping part 2 to be inserted and pushing and pulling the insertion plate part 1. In addition, a hand gripping the gripping part 2 is regulated not to be projected more downward than the insertion plate part 1 by a protection piece 13, when the plate part 1 inserted between the roof materials is pushed and pulled, the hand is prevented from coming into contact with a roof face. There by the nails and the machine screws attaching the roof material can be easily cut without damaging the roof material, and roof material replacement working is made easy.