a paper feeing cassette of an image forming apparatus includes a paper stacking plate on which a sheet of paper is stacked ; a lift unit placed under the paper stacking plate , lifting by a rotating pivot , the rotating pivot being connected to a driving motor using a connection portion and rotated , and ascending the paper stacking plate ; and a release unit separating the connection portion from the rotating pivot , disconnecting the driving motor from the rotating pivot , descending the paper stacking plate by its weight , and separating the sheet of paper from a pickup roller .