Provided is a method of controlling a fusing speed of an image forming apparatus. Determination is made as to whether a sheet of paper to be printed is a special-purpose sheet. Determination is made as to whether a length 1 of the sheet of paper is shorter than a distance L1 between a second transfer roller and a fusing unit. Determination is also made as to whether the length 1 of the sheet of paper is shorter than a distance L0 between a first transfer roller and the second transfer roller. Determination is made as to whether the length 1 of the sheet of paper is longer than the distance L0 between the first transfer roller and the second transfer roller.