In a sheet feeding apparatus for separating individual sheets (1b, 1c) of different stiffness from stacks (1d) thereof, the stack is pressed under the urgency of a spring force against separating rollers (9) and the sheet supply container (1) has an inclined front wall surface (10) on its front wall (4) upon which the stacked sheets are supported. A pair of arms (12) carrying separating elements (3) on their lower ends are carried on the supply container side wall (1a) for substantially parallel movement therealong. The arms (12) are implemented as linearly-movable switch sides (13) which are reciprocally displaceable between a lowered position in which the separating element end surfaces (15) rest against the supply container front wall surface (10) or the front region (11) thereof, and an upper or raised position in spaced apart relation to and providing a well-defined clearance (16) relative to the topmost sheet in the stack (1d).