A sheet storage device includes a case, a lift plate, and a lift attachment. The lift attachment is fixed, in a detachable manner, to a central portion of the lift plate in a width direction. The lift attachment supports a lower surface of the sheets stacked on the lift plate at a position higher than the upper surface of the lift plate. The lift attachment includes a base portion and a pair of arm portions. The pair of arm portions are respectively formed to extend from an end portion of the base portion that is on a downstream side in the sheet feed direction, to opposite directions in the width direction.