A capacity variable type twin rotary compressor may include a casing, a motor, a first cylinder having a first compression space, a second cylinder fixed to one side of the first cylinder and having a second compression space, first and second intakes respectively formed in the first and second cylinders and each connected to a gas intake pipe, first and second vane slits respectively formed in the first and second intakes first and second rolling pistons eccentrically coupled to the motor and respectively housed in the first and second compression spaces, first and second vanes slidingly received in the first and second vane slits, respectively, an expansion groove formed at the second vane slit separate from the inner space of the casing, and refrigerant switching valves that allow refrigerant of intake and discharge pressures to be supplied into the second compression space and the expansion groove, such that the second vane contacts the second rolling piston to perform a power driving or separates therefrom to perform a saving driving.