1. A file search method executed in a file search apparatus for searching for a file relevant to an application, the file search apparatus having an interface, a processor coupled to the interface, and a memory coupled to the processor, the file search method comprising the steps of: obtaining process information which includes an execution start time and file path of the application; identifying, from the obtained file path, a directory that serves as a start point in a search for a file relevant to the application, wherein the step of identifying a directory that serves as a start point in a search for a file relevant to the application includes the step of: setting a directory above a directory that stores the application as a parent directory based on the obtained file path; setting a directory that is created in the parent directory and that is contained in the obtained file path as a child directory; setting other directories created in the parent directory than the child directory as brother directories; comparing a creation time of the child directory with creation times of the brother directories; identifying the parent directory as the directory that serves as a start point in a search for a file relevant to the application in a case of which all of the brother directories have been created within a given period of time from the creation time of the child directory; identifying the child directory as the directory that serves as a start point in a search for a file relevant to the application in a case of which none of the brother directories have been created within the given period of time from the creation time of the child directory; and identifying the child directory and the brother directories that have been created within the given period of time from the creation time of the child directory as the directories that serve as start points in a search for a file relevant to the application in a case of which some of the brother directories have been created within the given period of time from the creation time of the child directory; and searching, with the identified directory as the start point, for a file accessed after the execution start time of the application.