There are four principles of environmental economics' cost burden theory: an ability principle, a benefit principle, a cause principle, and a commitment principle. The commitment principle is divided into the responsible commitment and the voluntary commitment. This paper considers the voluntary commitment through the case of the Japan-China Cooperative Fund for Victims of Chemical Weapons and Bio Land Cooperative. Taking the time axis into consideration, the cost burden theory can be grasped as follows. The ability principle and the benefit principle are based on the present. The cause principle and the responsible commitment are based on the past. And the voluntary commitment is based on the future. By considering the time axis, it may be possible to add new possibilities to the cost burden theory.