To provide a polycaprolactone copolymer producible using easily available materials and having a high degradability, its utilization method, and its manufacturing method and manufacturing equipment.

The polycaprolactone copolymer is produced in the manner that its mixture is heated and kneaded stepwise at temperatures in the order of 30-50°C, preferably 40°C, 50-70°C, preferably 60°C, 80-100°C, preferably 90°C, and 100-120°C, preferably 110°C, and further stepwise heated, pressurized and kneaded at temperatures in the order of 110-130°C, preferably 120°C and 130-150°C, preferably 140°C.