A rotary compressor has two compression capacities according to two different rotational directions of the driving shaft. The rotary compressor includes a driving shaft with an eccentric portion. A roller rotates on the shaft along an inner circumference of the cylinder. A vane installed in the cylinder continuously contacts the roller. An upper and a lower bearing are respectively disposed on the top and bottom of the cylinder. A disc shaped valve rotates between two positions and has at least one suction port for selectively supplying refrigerant inside the compression chamber according to the rotational direction of the driving shaft and at least one discharge port communicates with the compression chamber for discharging the compressed refrigerant. The refrigerant is supplied through a communication hole to a port formed on the outer valve.