A capacity-variable rotary compressor comprising: a cylinder installed in a hermetic casing and including a compression space in which a refrigerant is sucked to be compressed, an inlet connected to the compression space, and a vane slot formed at one side of the inlet; a rolling piston for transferring a refrigerant with performing an eccentric orbiting motion inside the compression space of the cylinder; a vane slidibly inserted into the vane slot of the cylinder, having an inner end coming in contact with the rolling piston so as to divide the compression space into a suction chamber and a compression chamber; a vane chamber connected to an outer end of the vane slot and separated from an hermetic space of the casing; a mode switching unit for contacting or separating the vane with/from the rolling piston depending on an operation mode of the compressor, having a common side connection pipe connected to the vane chamber so as to alternately supply suction pressure and discharge pressure to the vane chamber through the common side connection pipe; and a high pressure passage connected between the inside of the casing and the vane slot in a perpendicular direction or an inclined direction to a motion direction of the vane, characterised in that the compressor further comprises: a low pressure passage connected between the vane slot and the Z inlet, the low pressure passage formed at an opposite side of the vane slot to the high pressure passage, such that the vane contacts the inner side surface of the vane slot. a cylinder installed in a hermetic casing and including a compression space in which a refrigerant is sucked to be compressed, an inlet connected to the compression space, and a vane slot formed at one side of the inlet; a rolling piston for transferring a refrigerant with performing an eccentric orbiting motion inside the compression space of the cylinder; a vane slidibly inserted into the vane slot of the cylinder, having an inner end coming in contact with the rolling piston so as to divide the compression space into a suction chamber and a compression chamber; a vane chamber connected to an outer end of the vane slot and separated from an hermetic space of the casing; a mode switching unit for contacting or separating the vane with/from the rolling piston depending on an operation mode of the compressor, having a common side connection pipe connected to the vane chamber so as to alternately supply suction pressure and discharge pressure to the vane chamber through the common side connection pipe; and a high pressure passage connected between the inside of the casing and the vane slot in a perpendicular direction or an inclined direction to a motion direction of the vane, characterised in that the compressor further comprises: a low pressure passage connected between the vane slot and the Z inlet, the low pressure passage formed at an opposite side of the vane slot to the high pressure passage, such that the vane contacts the inner side surface of the vane slot. a low pressure passage connected between the vane slot and the Z inlet, the low pressure passage formed at an opposite side of the vane slot to the high pressure passage, such that the vane contacts the inner side surface of the vane slot.