Image forming apparatus conveniently upgradable to a duplex image forming apparatus

An image forming apparatus, comprising:

• sheet containing means for containing a plurality of recording sheets, said sheet containing means being located at a lower part of said image forming apparatus;
• first sheet path means arranged in a first side of said image forming apparatus;
• first sheet transferring means for sending each of said plurality of recording sheets, one by one, from said sheet containing means through said first sheet path means;
• image recording means for performing an image recording process relative to each of said plurality of recording sheets sent by said first sheet transferring means;
• ejecting means for switching between an ejection process and a duplex recording process relative to a back surface of each of said plurality of recording sheets, after completion of said image recording process on a front surface of each of said plurality of recording sheets;
• second sheet path means for receiving each of said plurality of recording sheets from said ejecting means, when said ejecting means switches to said duplex recording process, and said second sheet path means for transferring each of said plurality of recording sheets back to said image recording means, said second sheet path means being arranged in other sides of said image forming apparatus than said first side of said image forming apparatus in which said first sheet path means is arranged;
• and
• sheet flipping means for flipping each of said plurality of recording sheets in said second sheet path means, said sheet flipping means having a flipping space in which each of said plurality of recording sheets is flipped, without coming outside said image forming apparatus, said sheet flipping means being arranged along said second sheet path means.