A thermosetting bioplastic was formed by heating a bioplastic prepolymer consisting of glucose and modified MDI (carbodiimide-modified 4,4'-diphenyl methane diisocyanate). This plastic, formed by a hot stamping device, had the same quality (bending strength) as phenolic resin. However, the bending strength deteriorated after a long heating treatment. The optimum heating time was around 300 s and the cure ratio reached 60-80% at the average heating temperature of 430 K during the industrial manufacturing process. The cure ratio of the bioplastic prepolymer could be roughly estimated by measuring the change in color (hue value of microscopic image). The time courses of the cure ratio during heating could be simulated by a kinetic model. Both methods will be useful for process management during the production of thermosetting bioplastic as a replacement for phenolic resin. The results of this study will be very important for the industrial manufacturing of thermosetting bioplastic.