To provide a data carrier system that prevents a useless wakeups from taking place by surely identifying external disturbing radio waves.

In the data carrier system, consisting of a responder means and an interrogator means that wakes up when the interrogator means approaches the responder means to carry out communication by a microwave with respect to the interrogator means, the interrogator means is provided with a function of incorporating a low frequency AM modulation signal at the start of transmission of a microwave, and the responder means is provided with a function that wakes up, only when it receives the low-frequency AM modulation signal.