A filter device for a vacuum cleaner includes a casing having a collecting space therein, a suction opening through which air including dust is sucked, formed eccentrically at one side so that sucked air can be rotated and a discharge opening through which purified air is discharged. A filter is installed at an internal space of the casing, for filtering dust from air sucked through the suction opening. A filter cleaning unit is disposed at an outer circumferential surface of the filter, for cleaning the filter by being rotated by a rotation force of air sucked through the suction opening. A rotation restrainer is provided for restraining rotation of the filter cleaning unit when the filter cleaning unit reaches a topmost position. Accordingly, fine dust attached to the filter in cleaning is removed so that a channel of the filter can be prevented from being closed.