PROBLEM TO BE SOLVED: To provide a method and a program for supporting a planting plan, by which a proper planting plan taking a change of a plant with age into consideration is designed even for a person other than a specialist. SOLUTION: The method for supporting a planting plan comprises an input means 3 for memorizing a function 100 between a plant age and a three-dimensional shape derived for each kind of plants 41 in a computer 1 and inputting the position, the kind and the three-dimensional shape on planting ground 40 for each plant 41, a planning drawing preparation means 5 for preparing the planting planning drawing Iga in which the position, the kind and the three-dimensional shape for each plant 41 are recorded and a means for calculating the change of planting with age on the planting planning drawing Iga based on the function 100. A timber volume estimation formula 101 in response to the three-dimensional shape derived for each kind of the plants 41 and an estimation formula 102 for a carbon amount contained in response to the timber volume are memorized in a memory means 2 and the fixed amount of carbon dioxide (CO2) in air by planting is calculated by the means 6 for calculating the change with years. A relational expression 103 between the fixed amount of CO2of the plant and the absorbed amount of an air pollution substance is memorized in the memory means 2. The absorbed amount of the air pollution substance by the planting is calculated by the means 6 for calculating the change with age. COPYRIGHT: (C)2005,JPO&NCIPI