A device and a method for controlling a transmission power in a mobile terminal are provided. The device includes an antenna set in an optimized state, a memory including a power control table that includes transmission power control data for satisfying a Specific Absorption Rate (SAR) standard in a state where efficiency of the antenna is optimized, a sensor for detecting a distance between the mobile terminal and a user, a controller for receiving distance data from the sensor and for outputting transmission power control data corresponding to the distance data by referring to the power control table, and a power amplifier connected between a transmitter and the antenna for controlling transmission power of a signal according to the transmission power control data and for outputting the signal to the antenna.