A pair of combined cylinder blocks which are horizontally disposed are formed with wall portions extending from the boss portions of the cylinder blocks to the bottoms thereof. The wall portions define therebetween a swash plate chamber and an oil pan located beneath the swash plate chamber. The wall portions are each formed with a lubricating oil channel communicating the oil pan with a through bore formed in the cylinder block through which the drive shaft of the compressor extends. Due to a pressure differential between the swash plate chamber and the suction chambers of the pump, lubricating oil in the oil pan is led through the lubricating oil channels and gaps between the drive shaft and the through bores and supplied to radial bearings supporting the drive shaft in the through bores, thrust bearings supporting the swash plate and the sliding portions between the swash plate and the pistons to lubricate same. Further, the ends of the lubricating oil channels opening in the through bores are located at such axial predetermined locations as ensure suitable distribution of lubricating oil to the radial bearings and the thrust bearings.