An information storage medium includes storage unit for storing first, second, and third data composed of a data structure including identification information which identifies process target data, length information indicating data length of the process target data, and the process target data, communication unit for communicating with a medium processing device, and data processing unit for accessing the process target data included in the second data on the basis of a first command received via the communication unit, the first command specifying the identification information included in the second data and ordering processing of the process target data included in the second data, and subsequently accessing the process target data included in the first data on the basis of a second command including a preceding data specification and ordering processing of the process target data.