Provided are an IC card, an IC module and an IC card system that can improve the security. An IC card of embodiments has a generation unit and an authentication unit. The generation unit generates a second password that is a password for authenticating a card user based on a first password stored in a storage unit in advance, a predetermined parameter and a predetermined algorithm. The authentication unit compares a third password acquired from an external apparatus and provide second password, and determines the validity of the card user based on the comparison result.