The purpose of this paper is to reorganize cost adjustment factors of software development projects in estimating software development cost, and derive adjustment coefficients of application types and language types by analytical hierarchy process. We constructed a decision-making hierarchy of various criteria which determine the complexity of application types and language types, and conducted a survey on the pairwise comparison among alternatives. Finally, the cost adjustment coefficients of application types and language types were derived by analytic hierarchy process. This paper is the first study in which the analytic hierarchy process was applied to the field of estimating cost adjustment factors of software development projects.