The present invention is a cyclone dust collecting apparatus for a vacuum cleaner in which an air-whirling space and a contaminant collecting space are separated from each other. The cyclone dust collecting apparatus for the vacuum cleaner according to the present invention comprises a cyclone body connected to an extension tube; an inner cover provided at a lower side of the cyclone body, the inner cover having a hollow conical shape with an opened upper and lower ends; a grill unit through which the air is discharged, the grill unit being provided at a lower end of an air discharge tube of the cyclone body in the inner cover; and a contaminant receptacle for receiving a contaminant fallen from the inner cover, the contaminant receptacle being provided at a lower side of the inner cover.