A mobile terminal detecting an instantaneous deterioration in BLER and quickly converging an SIR into an appropriate target SIR, thereby preventing requesting an excessive transmission power from a base station and a method of controlling the mobile terminal are provided. The present invention relates to the mobile terminal including a target SIR control unit 105 that detects a burst error state indicating a deterioration in a communication environment, a burst error return state indicating a return of the communication environment, and a normal communication state indicating a good state of the communication environment based on whether a cyclic redundancy check is good, after detecting the burst error state, decreases the target SIR by a first decrease amount whenever an OK determination result of the cyclic redundancy check is obtained, detects a state in which the target SIR is decreased by a burst error return criterion that is a preset decrease amount, determines that the detected state is a burst error return state, and decreases the target SIR by a preset second decrease amount, and the method of controlling the mobile terminal.