1. A data managing method comprising the steps of: inputting data files by input processes, each of the data files being identified by respective data identification information; individually for each of the data files, defining permission data that associates user identification information with each of a plurality of different types of processes that can be performed on that data file, to indicate whether each such type of process is permitted for the data file; analyzing distribution data which associates, for each of the data files, each of processes which have been executed on the data file with user identification information identifying users who have executed the processes; determining whether or not each of processes which have been executed on one of the data files for an identified user, indicated in the distribution data, is permitted by the identified user by referring to the permission data; upon receiving a request to execute a process on the data file, updating the distribution data for the data file before obtaining a result of the determination step that all of processes that have been executed on said one data file are permitted; and forbidding execution of output processes for said one data file based on a result of said determination step that at least one of said processes that have been executed on said one data file is not permitted for the user who executed the process.