To specify the cause of absence of a restriction satisfying solution in a restriction satisfying problem for determining a restriction satisfying solution which satisfies a predetermined number of restriction conditions from preliminarily given variables.

A restriction condition management module reads all restriction conditions from a restriction condition database 1, forms all subsets of restriction conditions obtained by taking a partial group containing only a restriction condition having the top priority, and adding the remaining restriction conditions thereto one by one in the descending order of priority, makes a restriction satisfying engine 4 execute search of a restriction satisfying solution for each subset of restriction conditions, specifies a subset with a minimum element number of subsets in which no restriction satisfying solution is present from the execution result of search by the engine 4, specifies a restriction condition with the lowest priority in a subset with the minimum element number, and specifies this as the cause that no solution is present in the restriction satisfying problem.