A simulation apparatus which is capable of expressing a curling shape of a flexible medium such as a paper sheet in a simple manner, when evaluating functions of a conveying path. The behavior of a flexible medium conveyed in a conveying path is simulated. A display displays at least one component in the conveying path defined in advance on a display screen. A CPU interactively sets a shape of the flexible medium and an amount of curling of the flexible medium, the behavior of which in the conveying path is simulated on the display screen on which the component is displayed by the display.