A sheet container, which is incorporated in an image forming apparatus, includes a container body having a loading face to load a sheet thereon, an extension unit disposed extendable in a sheet feeding direction with respect to the container body to extend the loading face, a length regulator disposed movable in the sheet feeding direction with respect to the extension unit to regulate a sheet trailing end position in the sheet feeding direction, and a sheet size indicator having a strip-shape provided on the container body along with a moving direction of the extension unit as a reference of a position of the length regulator, having at least one sheet size mark to indicate a size of the sheet, and being variable in length in a longitudinal direction with respect to the container body along with movement of the extension unit.