The purpose of this study was to examine the expertise process of project manager for Information technology. Semi-structured interviews were conducted with 20 project managers who were at the professional level. The data collected from each participant were analyzed according to the modified grounded theory approach. A hypothetical model was constructed. As a result,5 category groups,20 categories,10 sub-categories,and 67 concepts were created based on the data. The major findings were as follows: in the growth from the first entry-level assignment to the professional level,there are certain improvement processes with reference to performance and personal skills. These two skill processes are intertwined based on the unique motivational project environment. In the process of development,the project manager is subject to positive effects from learning and stimulation from the surrounding people,such as seniors or co-workers,and customers.