A method and apparatus for calibrating a terminal is provided. The apparatus includes a modem; a transmission chain configured to process a signal input from the modem and transmit the processed signal via an antenna; a reception chain configured to process a signal received via the antenna and transmit the processed signal to the modem; and a connector configured to connect an output of the transmission chain and an output of the reception chain via an envelope detector and a switch configured to turn on/off the envelope detector, calibrate a DC offset voltage and I and Q signals of the transmission chain by inputting a one-tone signal of 1 MHz into the transmission channel via the modem in a state where the envelope detector is turned on, and calibrate a second order input intercept point (IIP2) characteristic value by adjusting the signal input into the modem via the reception channel.