Abstract: A gear-grinding multilayer grindstone includes: a first thread-shaped grindstone and a second thread-shaped grindstone that are fixed to each other, such that the first and second thread-shaped grindstones have a rotational axis that is common to the first and second thread-shaped grindstones; and a thread-shaped groove that is provided in a first outer circumferential surface of the first thread-shaped grindstone and a second outer circumferential surface of the second thread-shaped grindstone. The thread-shaped groove extends continuously over the first outer circumferential surface and the second outer circumferential surface. The second thread-shaped grindstone is constituted by abrasive cloths that are laminated on each other, and has a higher elasticity than the first thread-shaped grindstone.

Abstract: A gear-grinding multilayer grindstone includes a rough machining portion and a finish machining portion that are disposed adjacent to each other on a rotational axis. The rough machining portion includes a first core and a rough machining grindstone that is held on the first core. The finish machining portion includes a second core that is adjacent to the first core, and a finish machining grindstone that is held on the second core. The first core and the second core are fixed to each other, without the rough machining grindstone and the finish machining grindstone being fixed at least at outer peripheral portions thereof to each other.