A sheet-supplying device has a sheet-accommodating tray, a raising/lowering unit, a first position sensor, a second position sensor, a controlling unit. The raising/lowering unit raises and lowers the sheet-accommodating tray substantially. The first position sensor detects a first position indicating a position in the stacked direction of one end portion of a topmost sheet stacked in the sheet-accommodating tray. The second position sensor detects a second position indicating a position in the stacked direction of another end portion of the topmost sheet. The controlling unit controls the raising/lowering unit to raise or lower the sheet-accommodating tray based on both the first position detected by the first position sensor and the second position detected by the second position sensor so that one end of the topmost sheet in the stacked status is positioned at a prescribed position in the stacked direction.