A dust collector comprising: a first dust storing unit formed in a hollow cylindrical shape between an inner circumferential surface of a first dust container and an outer circumferential surface of a second dust container located in the first dust container, and configured to collect dust firstly-separated from air by a first cyclone; a second dust storing unit disposed to be surrounded by the first dust storing unit, and configured to collect fine dust secondly-separated from the air by second cyclones, located above the first cyclone, into a space formed by the second dust container; and a lower cover part coupled to the first dust container to form a bottom surface of the first dust storing unit and the second dust storing unit, and configured to simultaneously open the first dust storing unit and the second dust storing unit, such that the dust and the fine dust are simultaneously discharged, wherein the lower cover part comprises: a first cover coupled to the first dust container by a hinge and configured to open and close a discharge opening of the first dust storing unit; characterized in that the lower cover part further comprises a second cover connected to the first cover and configured to open and close a discharge opening of the second dust storing unit in response to a rotation of the first cover, wherein the first cover is provided with a first sealing member having a shape corresponding to the inner circumferential surface of the first dust container to seal the discharge opening of the first dust storing unit, and wherein the second cover is provided with a second sealing member having a shape corresponding to the inner circumferential surface of the second dust container to seal the discharge opening of the second dust storing unit a first dust storing unit formed in a hollow cylindrical shape between an inner circumferential surface of a first dust container and an outer circumferential surface of a second dust container located in the first dust container, and configured to collect dust firstly-separated from air by a first cyclone; a second dust storing unit disposed to be surrounded by the first dust storing unit, and configured to collect fine dust secondly-separated from the air by second cyclones, located above the first cyclone, into a space formed by the second dust container; and a lower cover part coupled to the first dust container to form a bottom surface of the first dust storing unit and the second dust storing unit, and configured to simultaneously open the first dust storing unit and the second dust storing unit, such that the dust and the fine dust are simultaneously discharged, wherein the lower cover part comprises: a first cover coupled to the first dust container by a hinge and configured to open and close a discharge opening of the first dust storing unit; characterized in that the lower cover part further comprises a second cover connected to the first cover and configured to open and close a discharge opening of the second dust storing unit in response to a rotation of the first cover, wherein the first cover is provided with a first sealing member having a shape corresponding to the inner circumferential surface of the first dust container to seal the discharge opening of the first dust storing unit, and wherein the second cover is provided with a second sealing member having a shape corresponding to the inner circumferential surface of the second dust container to seal the discharge opening of the second dust storing unit a first cover coupled to the first dust container by a hinge and configured to open and close a discharge opening of the first dust storing unit; characterized in that the lower cover part further comprises a second cover connected to the first cover and configured to open and close a discharge opening of the second dust storing unit in response to a rotation of the first cover, wherein the first cover is provided with a first sealing member having a shape corresponding to the inner circumferential surface of the first dust container to seal the discharge opening of the first dust storing unit, and wherein the second cover is provided with a second sealing member having a shape corresponding to the inner circumferential surface of the second dust container to seal the discharge opening of the second dust storing unit