1. A mobile communication terminal, comprising: a widget platform providing unit configured to generate an additional function expansion message based on expansion of an additional function of a widget, called by a widget script of the widget, wherein a widget is an application program executed at the mobile communication terminal that provides at least one function to a user at the mobile communication terminal without using a web browser, and to transmit the generated additional function expansion message; and a widget manager configured to receive the additional function expansion message, to determine a device application programming interface (API) library that includes the additional function, and to call the device API library directly by interpreting the additional function expansion message of the widget, wherein the calling of the device API library enables the widget to access a hardware device of the mobile communication terminal, without the widget using a procedure for directly accessing the hardware device.