In an information access system, an active contactless information storage device includes: a receiver unit adapted to sense a carrier of an RF signal at a first frequency for detection in a slave mode of operation and to be continuously ready to receive an RF signal at a second frequency different from the first frequency in a master mode of operation, and a transmitter unit for transmitting a response signal at the second frequency in response to reception of an information request signal in the slave mode of operation and for cyclically transmitting an information request signal at the first frequency in a transmission period and then go to an inactive state in a sleep period in the master mode of operation, under the control of the control unit. In the slave mode of operation, the control unit causes the transmitter unit and the receiver unit to go into the master mode of operation, when the receiver unit receives no information request signal in a first period of time longer than a plurality of the predetermined periods.