PURPOSE: To contrive simplification of a structure and the cost down, because of no necessary for an exclusive use of clutch for selecting a stepless transmis sion route, by connecting a turbine output shaft of fluid transmission to a stepped transmission route and a lockup output shaft to the stepless transmission route.

CONSTITUTION: In case of necessity for large drive power, a synchronously meshing mechanism 52 is placed in a position F connecting a low clutch 44 and releasing a lockup clutch 12d. Under this condition, turning force of an output shaft 10a is transmitted successively by order of a torque converter 12, turbine output shaft 36, forward drive side gear 42, forward output gear 48 and an output shaft 46. The above described transmission is performed with stepped transmission by gears obtaining large drive power. In case of requiring only small drive power, when the lockup clutch 12d is connected from the above mentioned condition, a stepless transmission route, that is, turning force of a lockup output shaft 14 is transmitted successively by order of a drive pulley 16, V belt 24, driven shaft 28, forward drive gear 58 and the forward only side gear 48. Thus, the necessity for a clutch selecting the stepless transmission route is eliminated.