To suppress the increase of sliding resistance of synchronizing parts and secure space for the passage of lubricating oil by providing an inner side claw and an outer side claw with the inner side and outer side inclined contact faces of prescribed angles for spacing an inner synchronizing ring and an outer synchronizing ring at the time of rotation.

An inner side claw 26a is formed by forming a cutout part 40 opened to the hub side of an inner synchronizing ring and cut out in such a way as to be extended onto the edge side. An outer side claw 28a is erected on the hub side of an outer synchronizing ring and formed wide on the edge side. An inner side inclined contact face 26b and an outer side inclined contact face 28b opposed to the contact face 26b are formed at the inner side claw 26a and the outer side claw 28a so that the inner and outer synchronizing rings are spaced from each other, for instance, spaced from each other in the opposite direction, at the time of rotation.