An information access system including an information device that is adapted for radio communication with a reader/writer, the information device having a detection data acquisition unit acquiring detection data from a sensor, a detection data storage unit holding the most recent detection data, a first receiving unit detecting the reception of an RF signal, and a first transmission unit transmitting a response signal. The reader/writer is adapted for radio communication with the information device and includes a second transmission unit transmitting the information request signal, a second receiving unit receiving the response signal, an accumulation recording unit recording the received detection data, and a detection data accumulation unit accumulating, in the accumulation recording unit, the most recent detection data, and if other detection data has not been accumulated in the accumulation recording unit, accumulating the other detection data in the accumulation recording unit.