To provide a gear shaving machining method allowing shaving machining with high precision and provide a shaving tool being suitable for the gear shaving machining method.

A composite machine tool is provided with a main spindle 17 capable of attaching a gear to be ground and a tool shaft 18 movable relatively for the main spindle 17 to press a core supporting an open end side of the main spindle 17 for use. A shaving cutter 32 is attached to the tool shaft 18 so that a rotary shaft crosses shaft center of the tool shaft 18 substantially orthogonally. A cutter 32 is arranged with a crossing angle for the main spindle 17 to which the gear 20 to be ground is attached. The cutter 32 meshes with the gear 20 to be ground, and the gear 20 to be ground is rotated and driven by moving the cutter 32 along the direction of shaft center of the main spindle 17 while pressing the core in this condition to perform shaving machining.