Patent ID: 7720429

Claim:
An image forming apparatus comprising: a printing unit which prints an image onto a recording medium; a transportation path inside of the printing unit through which the recording medium is transported from a sheet-feeding cassette to a discharge tray, wherein a front end of the recording medium moves along the transportation path first; and a shutter arm unit, comprising: a shutter arm which is at a first position where one end of the shutter arm protrudes toward the transportation path, and which moves to a second position when the shutter arm retracts from the transportation path when the shutter arm is pushed by the front end of the recording medium moving along the transportation path, and a stopper arm, formed on the shutter arm, which protrudes toward the transportation path when the shutter arm retracts to the second position and blocks a front end of at least a second recording medium moving simultaneously with the first recording medium along the transportation path, wherein the stopper arm comprises: a free end which protrudes toward the transportation path when the shutter arm retracts to the second position; and a fixing end connected to the shutter arm, wherein the stopper arm is positioned upstream of the shutter arm.