The present invention relates to a method of implementing a security system for preemptively preventing a decrease in work efficiency due to leaked confidential secrets or the browsing of non work-related sites through a mobile terminal. A security manager implements an environment for allowing, blocking, or recording Internet usage in an independent mobile communication network in an area requiring security, uses a security system server to preregister information on mobile terminals of users who are expected to use the Internet, makes agreements on how personal information will be handled when outside visitors visit the network, registers information on mobile terminals of outside visitors with the security system server, and oversees the installation of a security app whenever necessary.