Abstract: A sheet feeding mechanism has a pick up roller which picks up one sheet from a pile on a tray and sends It to contact between a separation roller and a retardation roller. A shaft which positively rotates in a sheet feeding direction is provided with a first gear and the separation roller via an arm pivotable about the shaft and a spring clutch. The arm carries a second gear which receives rotary power from the first gear, a third gear engaged with the second gear and the pick up roller connected with the third gear. The arm is biased upwardly and a negative torque is applied to the second or third gear. Below the separation roller, provided is the retardation roller which is mounted on another shaft via a torque limiter and pressed against the separation roller. The another shaft rotates in a direction opposite the sheet feeding direction. Up and down movement of the pick up roller is mechanically controlled.