Transfer belt unit and image forming apparatus having the same

A transfer belt unit, comprising:

• a transfer belt circulating and traveling and transferring a toner image formed on a photosensitive body onto a printable medium, the transfer belt having axially opposed outer edges;
• a plurality of support rollers supporting an inner circumference of the transfer belt;
• and
• a pair of belt guides respectively attached to both outer edges of the inner circumference of the transfer belt and engaging a regulating portion of each support roller to allow the transfer belt to travel in a substantially straight line, each of the belt guides having a joint portion,
• wherein the joint portion comprises first and second ends separated from each other to be substantially parallel to each other and inclined with respect to a traveling direction of the transfer belt, and
• the second end is located rearwardly of the first end with respect to the traveling direction of the transfer belt, and an external edge of the second end is chamfered such that a thickness of the chamfered edge is less than a thickness of a remaining portion of the pair of belt guides.