To form a unit which can be easily combined with transmissions having various design or sizes, reduces occupied space, weight and manufacturing costs, can be applicable in a broad field, and is perfect itself.

A multi-clutch assembly unit 10 comprises: a housing 34; a first clutch 36 which has a first driving member 42 rotatably supported on a driving hub 44 in the housing 34, and a first driven member 46 rotatably supported on a first driven shaft in the housing 34; a second driving member 62 coaxially arranged on a bore side of the first driven member 46, and rotatably supported on the driving hub 44; a second clutch 38 which has a second driven member 64 rotatably supported on a second driven shaft; and a torsional damper 40 which has a function of damping torsional vibrations generated between a power source and the first and second clutches 36, 38, and is disposed between a power source and the driving hub 44.