To provide a new device for cutting a linear and arbitrary curved line by a circular saw capable of easily cutting, in the linear and arbitrary curved line, a carbon fiber reinforced plastic laminated sheet, a duralumin plate to form an airframe of an aircraft, sheet metal, a stone material, or an asphalt road or the like as arbitrary shaped high-precision products.

In the device 100 for cutting the linear and the arbitrary curved line by the circular saw, a central hole 6A of the circular saw 6 is fitted to a tool rotating shaft 2, and movably forward and backward pressed to the tool rotating shaft in the axial direction in such a manner that projecting outer peripheral edges 8A, 9A of a pair of cone bodies 8, 9 oppositely contact with both surface outer peripheral edges 6B, 6C of the circular saw. One of the cone bodies is pressed F to the one side of the circular saw with a resilient member 10, and the cone body of the other side is adjustably pressed by a pressing drive member 20. The circular saw has a straightly extended attitude, a deflecting attitude to a resilient member side, and a deflecting attitude to the pressing drive member by the cone body by the control of a pressing force F0 of the pressing drive member.