A dust collector for a vacuum cleaner, comprising: an outer case; a first cyclone installed within the outer case to filter out dust from air inhaled from an outside thereof and introduce the air from which dust has been filtered out into an inside thereof; a plurality of second cyclones accommodated in the inside of the first cyclone to separate fine dust from the air introduced to the inside of the first cyclone; and a cover member disposed to cover an inlet of the second cyclone, wherein cyclones disposed adjacent to each other among the first and the second cyclones (110, 120) limit a first space within the first cyclone, and the cover member forms a second space communicating with the first space between the inlet and the cover member; and a guide vane extended in a spiral shape along an inner circumference thereof and provided at the inlet to induce rotational flow in air introduced to an inside of the second cyclones through the first and the second space (S1, S2), characterized in that the dust collector further comprises: an outlet of each second cyclone installed to pass through a bottom surface of the first cyclone; an inner case for accommodating the outlet, the inner case being installed at a lower portion of the first cyclone to form a fine dust storage portion for collecting fine dust discharged through the outlet; a dust storage portion disposed between an inner circumference of the outer case and an outer circumference of the inner case for collecting dust filtered out through the first cyclone; and a lower cover which is hinge-coupled to the outer case to form a bottom surface of the dust storage portion and the fine dust storage portion, and rotated by the hinge to open the dust storage portion and the fine dust storage portion at the same time so as to discharge the dust and the fine dust at the same time. an outer case; a first cyclone installed within the outer case to filter out dust from air inhaled from an outside thereof and introduce the air from which dust has been filtered out into an inside thereof; a plurality of second cyclones accommodated in the inside of the first cyclone to separate fine dust from the air introduced to the inside of the first cyclone; and a cover member disposed to cover an inlet of the second cyclone, wherein cyclones disposed adjacent to each other among the first and the second cyclones (110, 120) limit a first space within the first cyclone, and the cover member forms a second space communicating with the first space between the inlet and the cover member; and a guide vane extended in a spiral shape along an inner circumference thereof and provided at the inlet to induce rotational flow in air introduced to an inside of the second cyclones through the first and the second space (S1, S2), characterized in that the dust collector further comprises: an outlet of each second cyclone installed to pass through a bottom surface of the first cyclone; an inner case for accommodating the outlet, the inner case being installed at a lower portion of the first cyclone to form a fine dust storage portion for collecting fine dust discharged through the outlet; a dust storage portion disposed between an inner circumference of the outer case and an outer circumference of the inner case for collecting dust filtered out through the first cyclone; and a lower cover which is hinge-coupled to the outer case to form a bottom surface of the dust storage portion and the fine dust storage portion, and rotated by the hinge to open the dust storage portion and the fine dust storage portion at the same time so as to discharge the dust and the fine dust at the same time. an outlet of each second cyclone installed to pass through a bottom surface of the first cyclone; an inner case for accommodating the outlet, the inner case being installed at a lower portion of the first cyclone to form a fine dust storage portion for collecting fine dust discharged through the outlet; a dust storage portion disposed between an inner circumference of the outer case and an outer circumference of the inner case for collecting dust filtered out through the first cyclone; and a lower cover which is hinge-coupled to the outer case to form a bottom surface of the dust storage portion and the fine dust storage portion, and rotated by the hinge to open the dust storage portion and the fine dust storage portion at the same time so as to discharge the dust and the fine dust at the same time.