A sheet-supply cassette including a main member which is open upward and which is adapted to store a plurality of recording sheets which are stacked on each other and each one of which is separated from the other recording sheets, and is fed in a sheet-feed direction, by a sheet feeder; an inclined sheet-separate plate which is provided in a downstream-side portion of the main member as seen in the sheet-feed direction, and which cooperates with the sheet feeder to separate the each recording sheet from the other recording sheets; and a plurality of back-surface support portions which are formed integrally with the downstream-side portion of the main member, such that the back-surface support portions are distant from each other in a perpendicular direction substantially perpendicular to the sheet-feed direction. The inclined sheet-separate plate is detachably attached to the back-surface support portions such that a back surface of the inclined sheet-separate plate is supported by the back-surface support portions.