1. A method of improving the boot speed of a mobile communication terminal equipped with a detachable UIM (user identification module), the method comprising the steps of: a) handing over controllership, from a UI (user interface) task which is responsible for an initial UI process at boot time, to a UIM task in a process of reading a phonebook stored in the UIM during booting; b) setting parameters necessary for reading the phonebook stored in the UIM; c) reading records composing the phonebook one by one and copying each record into RAM after the setting of the parameters is completed; and d) handing over the controllership to the UI task after the UIM task copies the records composing the phonebook into the RAM.