An apparatus includes an input-side rotating member 2 driven by an engine (driving source) 90, an output-side rotating member 3 for driving an input member, such as a gear part 25 of a rear differential (driving-force distributing mechanism) 97 between wheels, a friction clutch 4 arranged between the input-side rotating member 2 and the output-side rotating member 3, a carrier housing (stationary member) 5 capable of accommodating the rear differential 97 and the friction clutch 4, an oil accommodating space (lubricant accommodating space) S formed in the stationary member 5 and an oil pump 6 driven by the output-side rotating member 3 to supply the friction clutch 4 with oil 600.