A planetary gear reduction mechanism is provided in a housing for making up a revolving apparatus, and the planetary gear reduction mechanism is constituted by a sun gear, a plurality of planetary gears, and a carrier. Lubricating oil for lubricating the planetary gear reduction mechanism is stored in the housing. A doughnut-shaped guide member for covering meshing portions of the sun gear and the planetary gears and for receiving the lubricating oil scattered from the meshing portions and guiding it to planetary gear bearings is provided at an upper position of the planetary gear reduction mechanism. Hence, the lubricating oil which is scattered from the meshing portions of the sun gear and the planetary gears can be efficiently guided to the planetary gear bearings through the doughnut-shaped guide member.