Activity Pattern Analysis(APA) is the methodology to Design the functions of information systems, to Estimate the monetary value of IS based on Activity Based Costing, to Acquire feasibility of IT Project. This study shows APA case in Health Check-up Service Organization (G-Center) and the Utility of APA. G-Center had acquired Five Outcomes through APA: (1) IT Strategy, (2) IT Project Goals, (3) Transformed Business Process, (4) Functional Blueprint of Information Systems, (5) IT Project budget and its feasibility. APA consists of three analysis processes; Activity Separation, Activity Rearrangement, Activity Costing. APA is flexible in determinating the range and the time of analysis, and is able to expand the Actors(as analysis objects) based on the purpose of analysis by researcher. Eventually APA can be used to do internal IT Management effectively.