Abstract: There is provided a management system including a first calculation unit, a second calculation unit, a storage unit, and a credit management unit. The first calculation unit calculates an increase amount of credit based on the purchase mass and the parameter representing the degree of reduction in environmental load in accordance with the purchase of plastic materials. The second calculation unit calculates a decrease amount of credit in accordance with either the transfer or production of the product. The storage unit stores an initial balance. The credit management unit updates a credit balance based on the initial balance, the increase amount, and the decrease amount.