A method for simulating the behavior of a flexible medium which is conveyed along a conveying path constructed of a pair of conveyor rollers includes the steps of dividing the surfaces of the conveyor rollers into a contact region and a non-contact region and setting a first peripheral speed and a second peripheral speed for the contact region and the non-contact region, respectively, and performing a simulation under a condition that a conveying force corresponding to the difference between the second peripheral speed and a moving speed of the flexible medium is applied to the flexible medium when the flexible medium reaches the non-contact region of the conveyor rollers and a condition that the flexible medium is conveyed at the first peripheral speed when the flexible medium reaches the contact region of the conveyor rollers.