PURPOSE: To provide a transmission for an automobile that is very small and can shorten its length to a minimum by making the transmission such that inclination and radial displacement of a ring wheel can be prevented through a proper method, and providing a planetary coupling that operates as a reversing device.

CONSTITUTION: A planetary support 3 and a ring wheel 8 of a planetary coupling 1 include a means, which selectively allows that either the ring wheel 8 be locked or the planetary support 3 be coupled to a sun wheel 6. Furthermore, at least one bearing 9, which is arranged in the radial direction in a region between the ring wheel 8 and the planetary support 3, is disposed between the ring wheel 8 and the planetary support 3. The bearing 9 and the planet wheels 4, 5 are mutually arranged, in such a way that they coincide with at least one mutual radial plane, in other words, a transverse plane through rotation axes of a first shaft 2 and a second shaft 7.