Disclosed is a sheet feeding device capable of prolonging the durability life span of the retard roller with a simple structure with ease and an image forming apparatus which includes the sheet feeding device. The sheet feeding device includes a feed roller 102 which rotates in a sheet feed direction, a retard roller 103 which is able to rotate in a reverse direction to the sheet feed direction which forms a separation nip portion. A torque limiter 202 which is interposed between a drive shaft 202b and a roller shaft 103b of the retard roller 103 to transfer a predetermined torque of the reverse direction to the retard roller 103; and a speed changing device 301 which is interposed between an output shaft 202a of the torque limiter 202 and the roller shaft 103b to change a magnitude of the predetermined torque transferred to the retard roller 103.