As the integrated and large-scale information is extended due to an advanced information system, a possibility of leaking out privacy increases as the time passes by. As a result, the necessity of using a privacy impact assessment (PIA) is emphasized because it can analyze and minimize the element of invasion of privacy. However, an essential audit for personal information protection is not fulfilled because most of the information system audit supervises over physical, managerial, and technical security items of system architecture area so that general items are the only things being checked. Consequently, this paper proposes that in order to minimize the invasion of personal information, the privacy impact assessment should be done. It also presents a procedure and method of personal information protection audit according to the result of the assessment. After applying the suggested method to two projects, it was confirmed that the improvements for protecting personal information were drawn from this paper.