A capacity variable type rotary compressor, comprising: a casing having a discharge pressure state; a first cylinder mounted in the inner space of the casing, a second cylinder mounted in the inner space of the casing so as to be positioned at one side of the first cylinder, having a vane pressure chamber provided at a rear side of a vane that divides an inner space of the cylinder into a suction chamber and a compression chamber; an upper bearing installed to cover an upper side of the first cylinder; a lower bearing installed to cover a lower side of the second cylinder, having an extension portion for covering one side of the vane pressure chamber; a middle bearing for separating the first and second cylinders from each other, having an extension portion for covering another side of the vane pressure chamber; a suction pressure side connection pipe connected to the inner space of the second cylinder; a discharge pressure side connection pipe connected to the inner space of the casing; a common side connection pipe connected to the vane pressure chamber; and a mode switching valve connected to the suction pressure side connection pipe, the discharge pressure side connection pipe, and the common side connection pipe, for alternately connecting the suction pressure side connection pipe and the discharge pipe side connection pipe to the common side connection pipe, characterized in that a through coupling bolt couples extension portions (331, 422) of each of the middle bearing and the lower bearing to an edge portion of the vane pressure chamber of the second cylinder such that the extension portions (331, 422) hermetically seal the vane pressure chamber of the second cylinder. a casing having a discharge pressure state; a first cylinder mounted in the inner space of the casing, a second cylinder mounted in the inner space of the casing so as to be positioned at one side of the first cylinder, having a vane pressure chamber provided at a rear side of a vane that divides an inner space of the cylinder into a suction chamber and a compression chamber; an upper bearing installed to cover an upper side of the first cylinder; a lower bearing installed to cover a lower side of the second cylinder, having an extension portion for covering one side of the vane pressure chamber; a middle bearing for separating the first and second cylinders from each other, having an extension portion for covering another side of the vane pressure chamber; a suction pressure side connection pipe connected to the inner space of the second cylinder; a discharge pressure side connection pipe connected to the inner space of the casing; a common side connection pipe connected to the vane pressure chamber; and a mode switching valve connected to the suction pressure side connection pipe, the discharge pressure side connection pipe, and the common side connection pipe, for alternately connecting the suction pressure side connection pipe and the discharge pipe side connection pipe to the common side connection pipe, characterized in that a through coupling bolt couples extension portions (331, 422) of each of the middle bearing and the lower bearing to an edge portion of the vane pressure chamber of the second cylinder such that the extension portions (331, 422) hermetically seal the vane pressure chamber of the second cylinder.