Patent ID: 8494384

Claim:
An image forming apparatus comprising: a forming section that forms an image on a side of paper; a fixing section that is provided on a downstream side of the forming section to apply heat to fix the image onto the side of the paper; a paper reversing section that reverses a front and back of the paper having the image fixed onto a first side in the fixing section; a registration roller that is arranged on an upstream side of the forming section to receive paper to be conveyed, come into contact with the received paper, and send out the paper to the forming section; a first measuring section that is provided between the registration roller and the forming section to measure a first moisture content of the paper before an image is formed on the first side, and a second moisture content of the paper before an image is formed on a second side that is a side opposite to the first side, after the image is fixed on the first side; and a calculating section that calculates amount of change of a size of the paper on the basis of difference between the first moisture content and the second moisture content that are measured by the first measuring section.