Abstract: A software rental method is disclosed. A specific software and rental term information or permitted accumulative use time information of said specific software are written into a circulating medium. The software retained in the circulating medium is autonomously invalidated at a time point when a desired rental term defined by the rental term information expires or at a time point when an accumulative use period of time exceeds a limit defined by the permitted accumulative use time information. A cartridge used as a circulating medium for a rental software, comprises a counter to be set with a rental term. The counter is counted down in response to the clock signal from a clock generator. Access to a title storing memory unit in the cartridge is prohibited at a time point when the counter value becomes zero.