Disclosed is a rotary compressor having two compression capacities in clockwise and counterclockwise directions. The present invention provides a rotary compressor comprising: a driving shaft (13) being rotatable clockwise and counterclockwise, and having an eccentric portion (13a) of a predetermined size; a cylinder (21) having a predetermined inner volume; a roller (22) installed rotatably on an outer circumference of the eccentric portion (13a) so as to contact an inner circumference of the cylinder (21), performing a rolling motion along the inner circumference and forming a fluid chamber (29) to suck and compress fluid along with the inner circumference; a vane (23) installed elastically in the cylinder (21) to contact the roller (22); upper and lower bearings (24, 25) installed respectively in upper and lower portions of the cylinder (21), for rotatably supporting the driving shaft (13) and hermetically sealing the inner volume; suction (27) and discharge ports (26) communicating with the fluid chamber (299 so as to suck and discharge the fluid; a suction plenum (500) communicating with the suction ports (27) and preliminarily storing the fluid; and a compression mechanism configured to form different sizes of compressive spaces in the fluid chamber (29) depending on the rotational direction of the driving shaft (13).