To make it possible to attach a paper feed cassette to an image formation apparatus even if a retracting member moves from a position at which the retracting member is engageable with the paper feed cassette.

A sheet storage device includes: a storage member storing a sheet, and attachable/detachable to/from a device main body; an engagement member engageable with the storage member attached to the device main body; and urging means for urging the engagement member. The engagement member is movable between a first position at which the engagement member is engageable with the storage member attached to the device main body and a second position at which the engaged storage member is more retracted into the device main body than the first position. The storage member is retracted into the device main body by moving the engagement member engaged with the storage member to the second position by means of an urging force of the urging means. The storage member includes a moving unit moving the engagement member. The moving unit can move the engagement member from the second position to the first position against the urging force of the urging means when the storage member is attached to the device main body.