Patent ID: 8342513

Claim:
A sheet storage device comprising: a sheet storage portion that stores a sheet; a sheet supply opening portion that is formed from an upper end of a side wall of the sheet storage portion in a vertically downward direction; a lift plate that is arranged in the sheet storage portion such that the lift plate can be moved up and down; a wire with which the lift plate is hung; a winding pulley that moves the lift plate up to a predetermined position by winding the wire; an idle gear that engages with a gear portion formed in the winding pulley; and a torsion spring that includes a winding spring portion which is fitted to a rotation shaft of the idle gear and a first arm portion and a second arm portion which extend from the winding spring portion and that has the first arm portion fixed to a side of the sheet storage portion, wherein, with the sheet storage device removed from a body of an image forming apparatus, the winding pulley is reversely rotated by a weight of the lift plate, the lift plate is lowered and the second arm portion engages with an engagement portion provided on a side surface of the idle gear such that an upper surface of the lift plate on which no sheet is stacked is stopped in a substantially constant position equal to or higher than a lower end portion of the sheet supply opening portion.