A vacuum cleaner comprising: a cleaner body; and a dust collecting device, wherein the dust collecting device includes: an external case having a dust storage part therein; an upper cover installed to cover an upper portion of the external case; a lower cover rotatably coupled to a lower portion of the external case; a first cyclone installed within the external case, having a mesh filter to filter out dust and a foreign object from air sucked from the outside, and allowing air without dust and a foreign object to be introduced to the inside thereof; a second cyclone accommodated within the first cyclone and separating fine dust from air introduced to the inside of the first cyclone; a cleaning unit sweeping dust and a foreign object clinging on the mesh filter down along an outer circumferential surface of the mesh filter; and a rotary unit coupled to the mesh filter and relatively rotating the mesh filter with respect to the cleaning unit, wherein the first cyclone includes a housing coupled to a lower portion of the upper cover, wherein the cleaning unit includes a plurality of cleaning ribs extending in a downward direction so as to be in contact with an external circumferential surface of the mesh filter in the housing; characterized in that the cleaning unit includes a plurality of support ribs extending in a downward direction so as to be in contact with an internal circumferential surface of the mesh filter to support the mesh filter in the housing. a cleaner body; and a dust collecting device, wherein the dust collecting device includes: an external case having a dust storage part therein; an upper cover installed to cover an upper portion of the external case; a lower cover rotatably coupled to a lower portion of the external case; a first cyclone installed within the external case, having a mesh filter to filter out dust and a foreign object from air sucked from the outside, and allowing air without dust and a foreign object to be introduced to the inside thereof; a second cyclone accommodated within the first cyclone and separating fine dust from air introduced to the inside of the first cyclone; a cleaning unit sweeping dust and a foreign object clinging on the mesh filter down along an outer circumferential surface of the mesh filter; and a rotary unit coupled to the mesh filter and relatively rotating the mesh filter with respect to the cleaning unit, wherein the first cyclone includes a housing coupled to a lower portion of the upper cover, wherein the cleaning unit includes a plurality of cleaning ribs extending in a downward direction so as to be in contact with an external circumferential surface of the mesh filter in the housing; characterized in that the cleaning unit includes a plurality of support ribs extending in a downward direction so as to be in contact with an internal circumferential surface of the mesh filter to support the mesh filter in the housing. an external case having a dust storage part therein; an upper cover installed to cover an upper portion of the external case; a lower cover rotatably coupled to a lower portion of the external case; a first cyclone installed within the external case, having a mesh filter to filter out dust and a foreign object from air sucked from the outside, and allowing air without dust and a foreign object to be introduced to the inside thereof; a second cyclone accommodated within the first cyclone and separating fine dust from air introduced to the inside of the first cyclone; a cleaning unit sweeping dust and a foreign object clinging on the mesh filter down along an outer circumferential surface of the mesh filter; and a rotary unit coupled to the mesh filter and relatively rotating the mesh filter with respect to the cleaning unit, wherein the first cyclone includes a housing coupled to a lower portion of the upper cover, wherein the cleaning unit includes a plurality of cleaning ribs extending in a downward direction so as to be in contact with an external circumferential surface of the mesh filter in the housing; characterized in that the cleaning unit includes a plurality of support ribs extending in a downward direction so as to be in contact with an internal circumferential surface of the mesh filter to support the mesh filter in the housing.