The present invention provides a dust collecting apparatus for a vacuum cleaner, comprising: a first cyclone installed in a first case and configured to separate dust from air introduced thereinto together with foreign substances and to discharge the separated dust to a first dust storage unit; a second cyclone mounted above the first cyclone and configured to separate fine dust from the air from which the dust is separated by the first cyclone and to discharge the separated fine dust to a second dust storage unit; a compression device configured such that at least a part thereof performs normal rotation in one direction and reverse rotation in the direction opposite to that of the normal rotation along the outer peripheral surface of a second case having the second dust storage unit therein to compress the dust stored in the first dust storage unit; a screw rotatably installed above the compression device and having a guide vane spirally extending along the outer periphery thereof to guide the collection of dust into the first dust storage unit; a driving unit that transmits a driving force to the compression device to selectively enable the normal rotation and the reverse rotation of the compression device; and a gear unit installed between the compression device and the screw to enable the screw to perform normal rotation while the compression device performs the normal rotation and the reverse rotation.