PURPOSE: To improve oiling performance by disposing a cylindrical rotor having a spiral blade fitted in the outer periphery with longitudinally changed pitches and the axis directed vertically in a cylinder and providing an oil pump immersed in oil on the lower and of the rotor.

CONSTITUTION: A vertical fluid compressor 31 having the axis of an enclosed case 32 directed vertically accommodates a compression mechanism section 33 in the enclosed case 32 and DC brushless motor 34 for driving the same. The compression mechanism section 33 is composed of a cylinder 35 having both ends opened and a piston 36 of a cylindrical rotor fitted slidably in the cylinder and having a spiral blade 40a fitted in the outer periphery of the rotor with longitudinally changed pitches. The piston 36 is supported rotatably by main and auxiliary bearings 42, 48 on the upper and lower portions of the cylinder 35. A conical receptacle-shaped oil feeding pump 55 is provided on an auxiliary shaft 39 at the lower end of the piston 36 so that oil pumped up by driving the pump 55 is supplied through an oil hole 58 or the like to slidable parts.