A sheet storage device includes a sheet storage unit to store sheets, a regulating unit in the sheet storage unit, and a lifting unit. The regulating unit regulates a position of a rear edge portion of the sheets in a sheet conveyance direction and includes a supporting portion, an urging member, and a pressing portion having a pressing surface in which a position to be in contact with lower sheets is a pressing surface lower portion, and a position to be in contact with upper sheets located higher than the lower sheets is a pressing surface upper portion. The pressing surface can be in a first state, where the pressing surface upper portion is located downstream from the pressing surface lower portion in a pressing direction, or in a second state, where the pressing surface lower portion is located downstream from the pressing surface upper portion in the pressing direction.