This paper proposes a method to construct a student ID (identification) system using a cell phone. The student ID data are stored in the server. Each student receives the student ID data in each cell phone. The cell phone displays the character data (name, affiliation, etc.), the face image and the twodimensional symbol. As the face image displayed on the cell phone is large enough in comparison with the photograph size of the conventional ID card, the precision is improved when the examiner compares the displayed face image to the live face. The student ID can be used not only when the examiner?s terminal can communicate with the server, but also when it cannot communicate with the server. The cost for issuing or reissuing a student ID by using the proposed method is very low in comparison with the conventional student ID card. The prototype has been implemented and evaluated.