To arrange a clutch and a continuously variable transmission in a coaxially and compactly connected state and in a positively journalled state and easily ensure the layout space of reduction gear mechanism while facilitating the connection to the continuously variable transmission.

A power transmission is so constituted that the power of an engine is transmitted to a continuously variable transmission 3 by a clutch 2 and further transmitted to a driving propulsion part while changing the rotating speed of engine power by the continuously variable transmission 3. In this case, the clutch 2 is arranged coaxially with the continuously variable transmission 3, and this coaxial shaft is provided at a partition wall 301a of a case 301 through bearings 302, 303. The clutch 2 and a forward/reverse switching device having an input part and an output part and capable of switching the rotating direction of power to be outputted from the output part upon receiving power in a specified rotating direction to the input part are arranged in one chamber 304 partitioned by the partition wall 301a, while the continuously variable transmission 3 is arranged in the other chamber 305, and reduction gear mechanism 45 for transmitting power to a shift device 13 is arranged being connected to the other chamber 305 where the continuously variable transmission 3 is arranged.