An apparatus and method are provided for controlling power in sleep mode in a mobile communication terminal. A radio communicator including a power supply converts a radio signal received through an antenna into a baseband signal using a reference oscillating frequency of a voltage controlled oscillator. A radio frequency identification (RFID) tag generates power using an interrogation signal from a base station, and outputs a "wake-up" signal to be used to determine whether a radio signal has been received using the generated power. A controller controls the power supply to supply the power to the radio communicator in response to the wake-up signal from the RFID tag. Accordingly, an amount of power consumption in the mobile communication terminal can be reduced.