In a small and thin memory module for sharing data among electronic devices such as information processing apparatuses, a write prohibit state can be visually recognized. A conductive seal is attached to a predetermined position on a support member, thereby setting the memory module in the write prohibit state. The conductive seal visually indicates the write prohibit state. When the memory module is mounted in a connector section of a card-shaped holder, connector pins are electrically connected to each other via the conductive seal. Thus, a write prohibit mechanism is realized at low cost.