This paper proposes Stamp-On, a mobile guidance aid for museum visitors. Stamp-On equips a tangible interface in the form of a stamp, which is used as an input-device for visitors to show explanations on a mobile device such as an iPad. The explanations will give the corresponding information about exhibiting items with additional questions. By touching the screen of the mobile device with the Stamp-On near the corresponding item, she or he will get visual information. We have conducted a preliminary experiment with participants of school teachers in order to evaluate the effectiveness as an exhibition guidance system. The results have suggested that Stamp-On system is an attractive and effective learning aid for elementary school children visitors of a museum.