The importance of strategic operation on the IT outsourcing israpidly increasing. The selection process of IT outsourcer plays a critical role since the service quality determined by IT outsourcer is directly linked with each other. While the importance of the selection process is realized, it is still quite drift and subjective. This paper proposes an evaluation model that helps a decision group to select a proper IT outsourcer among alternatives by using Analytic Hierarchy Program, AHP. In this paper, the web system is designed the way that focuses on group decision making with a geometric mean method, GMM, of AHP for IT outsourcer selection.