A method of controlling a semiconductor memory card system including a host device incorporating a semiconductor memory card and communicating information with a user of the host device to warn the imminent end of the life of the memory card in the system is provided. According to one aspect, there is provided a method of controlling a semiconductor memory card, the method comprising creating end-of-life index data of the semiconductor memory card, reading the end-of-life index data in response to a command from a host device to the semiconductor memory card, creating an end-of-life warning status of the semiconductor memory card from the end-of-life index data based on a life control limit value, and sending a response containing the end-of-life warning status to the host device as a response to the command through the same communication line as that for the command.