A baffle plate (4) including a body portion (5), a cover portion (8, 9) and a seal member (88, 98), a final gear (25) and a driven sprocket (DS) disposed in an accommodating chamber (Sa, Sb) of the baffle plate (4), an oil pump (OP) serving as a source of oil (OL) for lubrication, and an oil pan (16) are provided. At least one of the body portion (5), the cover portions (8, 9) and the seal members (88, 98) includes a material that shrinks as the temperature of the oil (OL) decreases. The baffle plate (4) is dimensioned such that a gap (CL1, CL2) is sealed by the seal member (88, 89) when the temperature of the oil (OL) is equal to or higher than a predetermined oil temperature and an aperture (CL′) is formed when the temperature of the oil (OL) is less than the predetermined oil temperature.
The gap (CL1, CL2) is the gap between an inner circumference of an outer wall portion (62, 72) of the body portion (5) and each of a base portion (80) of the cover portion (8) and a base (90) portion of the cover portion (9).