A medium feeding unit having an improved structure for sensing that the number of print media loaded onto a loading plate is equal to or exceeds a predetermined remaining number, and an image forming apparatus having the same. The medium feeding unit includes a sensor that outputs sensing signals having different voltages according to quantities of received light. The medium feeding unit also includes a plurality of actuators that sense the number of print media on a loading plate, differentially intercept the sensing area of the sensor thus changing the voltage level of the sensing signal, and therefore signal the medium feeding unit when the number of print media on the loading plate falls below the predetermined remaining number.