Tool, gear machining apparatus, and method of machining gear

A tool comprising:

• a first tool member including first machining blades formed on an outer circumferential surface of a disk-shaped first tool body so as to be parallel to a rotation axis of the first tool body, the first machining blades performing first machining on a workpiece;
• and
• a second tool member including second machining blades which are formed on an outer circumferential surface of a disk-shaped second tool body so as to be twisted with respect to a rotation axis of the second tool body and which have a blade length along a direction of the rotation axis of the second tool body longer than that of the first machining blades, the second machining blades performing second machining on the workpiece,
• wherein, in a state in which the first tool member and the second tool member are combined such that the respective rotation axes of the first tool body and the second tool body are coaxial with each other, the machining blades of the first tool member are formed so as to protrude in the direction of the rotation axes from the first tool body toward the second tool member, and the machining blades of the second tool member are positioned at predetermined intervals in a circumferential direction relative to protruding portions of the machining blades of the first tool member.