To provide a motive-power transmission device for a vehicle including a torque converter, a gearbox, and a clutch for cutting off the transmission of motive power between the input shaft of the gearbox and the turbine of the torque converter. The gearbox is accommodated in the crankcase, and the motive-power transmission device is compact in the axial direction of the crankshaft. A motive-power transmission device for a vehicle includes the crankshaft and the input shaft of the gearbox journaled freely rotatably in the crankcase, their axes being parallel to each other; the torque converter is mounted on one end portion of the crankshaft; and the clutch is separated along the axial direction of the crankshaft from the torque converter and so mounted on one end portion of the input shaft that part of the clutch overlaps the torque converter as seen in the axial direction of the crankshaft.