To dry and crush cogongrass, ditch reed, silver grass, rice straw, chaff, stems of tobacco and corn, and branches and leaves of soybean, adzuki bean and tomato, of grass plants or branches and leaves of cedars, pruned branches of apple, pine leaves, and bamboos of woody plants, and to form the crushed materials into pellets.

Water content of the cogongrass, ditch reed, silver grass, rice straw, chaff, stems of tobacco and corn, and branches and leaves of soybean, adzuki bean and tomato of grass plants in a harvested state is evaporated by drying so that the water content is within a range of 8-25%, and the resulting materials are cut into strips. Further, the strips are crushed into grains each having a size passing through the mesh space of 1/2 times the diameter of the pellet. The crushed cogongrass, ditch reed, silver grass, rice straw, chaff, stems of tobacco and corn, and branches and leaves of soybean, adzuki bean and tomato are formed to have a pellet shape at a low forming temperature by using a pelletizer (pellet forming machine). The diameter of each pellet is 4-25 mm.