The invention provides a rotary compressor used to structurally simplify a laminae which divides a cylinder into a low-pressure chamber and a high-pressure chamber. In addition, the invention providesa multi-stage rotary compressor, the manufacturing method thereof and a defrosting device used in a coolant loop. The rotary compressor(10)comprises a first and a second rotary compressing units(32,34) which are driven via an electromotor(14) arranged in a sealed container(12). The first rotary compressing unit(32)is composed of an upper cylinder(38), a swinging piston(110) for a roller(112)whichis connected with an eccentric unit(42)on the rotary shaft(16)of the electromotor(14) and eccentrically moves inside the upper cylinder(38), and a laminae(114) which is molded on the swinging piston(110) and protrudes in the radial direction from the roller(112)to divide the upper cylinder(38)into a low-pressure chamber and a high-pressure chamber. A retaining member is arranged to retain the laminae(114) of the swinging piston(110)in a sliding and swingy mode.