In an image forming method, an electrostatic latent image formed on a surface of a photoreceptor is developed into a developer image with a developer, and a printing paper transported on a transfer belt is brought into contact with the surface of the photoreceptor so as to transfer the developer image onto the printing paper. The printing paper is transported in a proper transport direction, in which a projection generated in one direction on the printing paper as a result of cutting the printing paper in a printing paper manufacturing process does not face a surface of the transfer belt at a leading edge of the printing paper being transported on the transfer belt. In this way, even in the presence of the projection generated when the printing paper is cut, the printing paper naturally strips off from the surface of the photoreceptor, thereby preventing toner contamination caused by a striping claw in contact with the leading edge of the printing paper.