This paper reports the development of simulation software and control logic for the lateral position control of a moving web in roll-to-roll (R2R) systems. A mathematical model is described first to explain the lateral dynamics of a moving web. Based on the model, simulation software named LACOSIM is designed and implemented to simulate the lateral dynamics and also to control the lateral position error of a web in R2R systems. As a lateral control method, fuzzy control logic is developed, embedded in LACOSIM, and verified by the simulations with sine and step input errors. In addition, a tabletop R2R hardware simulator is implemented as an experimental apparatus. Both the simulation software and the hardware simulator are considered as useful tools for the development of a web guide system for R2R systems.