A carbon offset credit calculation system utilizing waste oil comprising: a first terminal device (10, 20), which inputs information relating to waste oil regarded as a biomass resource; a second terminal device, which is owned by a fuel manufactory and inputs information relating to biofuel, which is purified from waste oil, wherein the fuel manufactory produces the biofuel based on the waste oil; a third terminal device (40, 50), which is owned by a site consuming biofuel, inputs information relating to power generation and fuel consumption; a carbon offset credit calculation server, which calculates a carbon offset amount based on information input by the first terminal device (10, 20), the second terminal device, and the third terminal device (40, 50), and calculates a carbon offset credit based on the carbon offset amount; wherein the first terminal device (10, 20), the second terminal device, the third terminal device (40, 50), and the carbon offset credit calculation server, are connected to one another via a network, wherein the first terminal device (10, 20), the second terminal device and the third terminal device (40, 50) comprise an input unit and a transaction unit, adapted to transact data between the terminal device (10, 20, 30, 40, 50) and the carbon offset credit calculation server via the network, wherein the information being input by the input unit of the first terminal device (10, 20) is a collected waste oil amount from the first terminal device (10, 20) located at a collection site, wherein the information being input by the input unit of the second terminal device is a biofuel production amount, wherein the information being input by the input unit of the third terminal device (40, 50) is an actual biofuel power generation amount and an actual biofuel consumption amount by a boiler or an incinerator, wherein the carbon offset credit calculation server comprising: a communication unit adapted to communicate data with the first terminal device (10, 20), the second terminal device and the third terminal device (40, 50) via the network a; a calculation unit adapted to calculate J z the carbon offset amount based on the obtained values via the communication unit and also adapted to calculate the carbon offset credit based on said carbon offset amount; and a memory, wherein the calculation unit is adapted to calculate the carbon offset amount by multiplying the actual biofuel power generation amount, which is obtained via the communication unit, with a CO2 emission coefficient. a first terminal device (10, 20), which inputs information relating to waste oil regarded as a biomass resource; a second terminal device, which is owned by a fuel manufactory and inputs information relating to biofuel, which is purified from waste oil, wherein the fuel manufactory produces the biofuel based on the waste oil; a third terminal device (40, 50), which is owned by a site consuming biofuel, inputs information relating to power generation and fuel consumption; a carbon offset credit calculation server, which calculates a carbon offset amount based on information input by the first terminal device (10, 20), the second terminal device, and the third terminal device (40, 50), and calculates a carbon offset credit based on the carbon offset amount; wherein the first terminal device (10, 20), the second terminal device, the third terminal device (40, 50), and the carbon offset credit calculation server, are connected to one another via a network, wherein the first terminal device (10, 20), the second terminal device and the third terminal device (40, 50) comprise an input unit and a transaction unit, adapted to transact data between the terminal device (10, 20, 30, 40, 50) and the carbon offset credit calculation server via the network, wherein the information being input by the input unit of the first terminal device (10, 20) is a collected waste oil amount from the first terminal device (10, 20) located at a collection site, wherein the information being input by the input unit of the second terminal device is a biofuel production amount, wherein the information being input by the input unit of the third terminal device (40, 50) is an actual biofuel power generation amount and an actual biofuel consumption amount by a boiler or an incinerator, wherein the carbon offset credit calculation server comprising: a communication unit adapted to communicate data with the first terminal device (10, 20), the second terminal device and the third terminal device (40, 50) via the network a; a calculation unit adapted to calculate J z the carbon offset amount based on the obtained values via the communication unit and also adapted to calculate the carbon offset credit based on said carbon offset amount; and a memory, wherein the calculation unit is adapted to calculate the carbon offset amount by multiplying the actual biofuel power generation amount, which is obtained via the communication unit, with a CO2 emission coefficient. a communication unit adapted to communicate data with the first terminal device (10, 20), the second terminal device and the third terminal device (40, 50) via the network a; a calculation unit adapted to calculate J z the carbon offset amount based on the obtained values via the communication unit and also adapted to calculate the carbon offset credit based on said carbon offset amount; and a memory, wherein the calculation unit is adapted to calculate the carbon offset amount by multiplying the actual biofuel power generation amount, which is obtained via the communication unit, with a CO2 emission coefficient.