IMAGE FORMING DEVICE

PROBLEM TO BE SOLVED: To provide an image forming device capable of correctly and speedily correcting a meander in a belt member. SOLUTION: This color printer 10 having a transfer carrying belt 12, as the belt member, stretched between plural rollers has a belt-meander correction mechanism for correcting a meander in the belt 12 by moving a correction roller 23. The printer also has an image forming unit 11d for writing a pattern consisting of a specific toner image onto the belt 12, a detection means 43 for detecting a pattern written on the belt 12, and a CPU for detecting an amount of belt meander based on the position of the detected pattern 41 and also determining an amount of the movement of the correction roller 23 by the belt-meander correction mechanism.