In a method of resolving a contribution ratio to soil contamination by a plurality of polluters through a sequential extraction scheme and a stable isotope analysis scheme, Pb stable isotopes are eluted at 5 types of “cation exchange fraction”, “carbonate fraction”, “iron-oxide and manganese hydroxide-fraction”, “organic matters and sulfide fraction”, and “residual fraction” existing at other types and separated from each other in each step. The Pb stable isotopes obtained in each step are analyzed. The contribution ratio to soil contamination by the polluters is resolved through a predetermined resolving equation using the content of a Pb stable isotope in each step based on the content ratio of the Pb stable isotopes. The Pb stable isotopes are 206Pb and 207Pb.