The present disclosure relates to a cyclone dust collecting apparatus for a vacuum cleaner having a high fine dust collecting efficiency. The cyclone dust collecting apparatus includes a first cyclone having an air suction hole through which dust-laden air is drawn-in, the first cyclone forcing the dust-laden air to downwardly whirl in a space under the air suction hole so as to centrifugally separate dust from the dust-laden air; a second cyclone disposed inside the first cyclone, the second cyclone forcing semi-clean air entering from the first cyclone to downwardly whirl so as to centrifugally separate fine dust from the semi-clean air; and an air guiding member forcing the semi-clean air discharged from the first cyclone to directly enter the second cyclone and, the air guiding member having a plurality of guiding blades radially disposed in at least one circular shape based on a vertical axis of the second cyclone.