To provide gear shaped cutting device and method capable of suppressing degradation of tooth shape accuracy and accurately machining a gear.

This gear shaped cutting device comprises a tool shaft 2 mounted. with a gear cutting tool 1 such as a pinion cutter and a driving means 3 for rotating the tool shaft 2. A workpiece is cut by the gear cutting tool 1 while the workpiece and the gear cutting tool 1 are relatively rotated. A control means keeps a cutting reaction force about the core of the tool shaft 2 substantially constant.