Abstract: The present invention aims to provide an authentication system that can accurately identify a genuine product. In an authentication system, a host instructs an authentication chip master to start authentication. In conjunction with the authentication start execution instruction, the host instructs a timer counter to start timer counting. In response to the authentication start execution instruction from the host, the authentication chip master outputs a challenge code to an authentication chip slave. The authentication chip slave performs an encryption process with respect to the challenge code. Then, the authentication chip slave outputs a response code obtained as the result of the encryption process, to the authentication chip master. Then, the authentication chip master performs a response code matching process, and outputs the authentication result to the host.