To sufficiently restrain heat generation caused by stirring of oil, and to supply oil in an amount required and sufficient for an oil seal member.

An upper half of a partition member 30 is notched and removed, and thereby an oil level can be lowered than the oil seal member 12. As a result, the oil scraped by a notched part 10a of a retainer 10 can be splashed to a part near the oil seal member 12. Therefore, even when the oil seal member 12 is not dipped in the oil level, the oil in the amount required and sufficient for the oil seal member 12 can be supplied. Further, the oil amount can be reduced, and the heat generation by stirring of the oil can be sufficiently suppressed to be low.