To provide a primer design device which can recognize the presence or absence of a mutation or a polymorphic site to automatically produce the information on a target primer.

A program comprises a step for obtaining information related to a base sequence of a gene to be replicated, a step for obtaining information related to the position of mutation or polymorphism in the base sequence of the gene to be replicated, and a step (S43, S45) for producing a primer satisfying prescribed conditions including a condition related to the mutation or polymorphism by using the information related to the base sequence of the gene to be replicated or by using the obtained information related to the position of mutation or polymorphism in the base sequence of the gene to be replicated. Thus, the information on a primer not containing and certainly containing the mutation or the polymorphism therein can automatically be produced, due to produce the information on the primer with the information related to information related to the position of mutation or polymorphism in the base sequence of the gene to be replicated.