CONTACTLESS DATA COMMUNICATION SYSTEM AND CONTACTLESS IC TAG

A contactless data communication system includes: a first and a second contactless integrated circuit tags each including an unique identifier; and a reader-writer for reading out and writing in data in a contactless state with the first and the second contactless integrated circuit tags. The first integrated circuit tag includes: a data detection unit for detecting data; a data determination unit for determining data detected by the data detection unit; and a data transmission unit for transmitting a determination result of the data determination unit to the second contactless integrated circuit tag. Here, the reader-writer and the first and the second contactless integrated circuit tags performing a contactless data communication therebetween, using an induction field; and the first contactless integrated circuit tag creating and electrical power from the induction field generated by the reader-writer, and the utilizing the electrical power so as to perform a contactless data communication with the second contactless integrated circuit tag.