To provide an image forming apparatus that can reduce density unevenness of an image even when the image is formed on a recording medium having surface irregularity.

An image forming apparatus comprises: a calculation section 123; a determination section 125; and a secondary transfer section counter roller. The calculation section 123 specifies paper thickness information for calculating difference of paper thickness from respective pieces of thickness information. Here, the thickness information corresponds to detection results in which thickness of recording sheet of paper being conveyed is sequentially detected, and indicates the thickness of recording sheet of paper. Then, the calculation section 123 calculates the difference in the paper thickness for the recording sheet of paper P using the specified paper thickness information. The determination section 125 determines whether or not the calculated difference in the paper thickness of the recording sheet of paper is a first threshold value or more. When the paper thickness concerned is the first threshold value or more, the secondary transfer section counter roller transfers an image on the recording sheet of paper using at least an AC voltage.