Finite element analysis (FEA) was conducted to investigate the cutting process of a single-layer PET film during rotary die cutting. In a roll-to-roll system, cutting blades formed on rollers were modeled as rigid bodies, while the PET film was modeled as an elastoplastic material using a two-dimensional approach. Stress-strain behavior of the film was measured through experimental tensile testing and used as input data for FEA. Force-displacement data from vertical cutting experiments of PET film were collected to validate the FE model and compared with simulation results. Stress distribution of the film and cutting force per unit thickness during the rotary cutting process were analyzed. The cutting force and range of effective cutting angles were proportional to tip angle of the blade within a range of 25 to 60 degrees, showing a noticeable change in proportionality slope at a tip angle of 40 degrees. As the film tension increased, the cutting force in thickness direction decreased, while that in longitudinal direction remained almost constant. Errors in film feed velocity significantly affected the cutting force. When the film moved slightly slower than the reference velocity, the cutting force was minimized due to reduced contact between the film and blade surface.