A toner container attachment detecting device includes a reader-writer, a shutter made with an electrically conductive material and provided movably between an open position where the shutter is kept from influencing a carrier wave radiated from an antenna of the reader-writer and a covering position where the shutter influences the carrier wave, and first and second displacing portions. When the toner container is attached to an apparatus body, the first displacing portion displaces the shutter to the open position. When the toner container is removed from the apparatus body, the second displacing portion displaces the shutter to the covering position. A radio field intensity detecting section of the reader-writer detects a radio field intensity of the carrier wave and a determining section of the reader-writer determines, based on a detection result of the radio field intensity detecting section, whether or not the toner container is attached to the apparatus body.