The invention relates to a method of managing files. In this invention, a method of managing a file stored in an external memory device of a computer having an application that starts when it is read by the computer consists of a step of accepting an instruction for starting up the application, and a step of automatically deleting the application program from the external memory device when the started application terminates. This file managing method can automatically delete the application program from the external memory device when the started application terminates.