A platform security apparatus and a method thereof are capable of protecting a mobile communication terminal from an abnormal or unintended operation of an application program installed over a platform of the mobile communication terminal. An authentication key is created with respect to each function of an application program, and the authentication key and an identifier of the application program are associated with each other and stored. An authentication process is performed by comparing an authentication key and an identifier of an application program registered as function parameters with an authentication key and an identifier of the application program which have been stored, when the application program calls the function.