An object of the present invention is to increase measurement precision for measuring errors of a quadrature demodulator. An error measurement device 10 receives an I signal and a Q signal from a quadrature demodulator 4 for demodulating a signal to be demodulated including multiple carrier signals respectively different from each other in frequency, and measures a gain imbalance which is a ratio of the amplitude of the Q signal to the amplitude of the I signal. Further, the error measurement device 10 includes an I-signal amplitude deriving unit 14I which derives the amplitude of the I signal for the respective carrier signals, a Q-signal amplitude deriving unit 14Q which derives the amplitude of the Q signal for the respective carrier signals, a carrier amplitude ratio deriving unit 16a which derives a ratio of the amplitude of the Q signal to the amplitude of the I signal for the respective carrier signals based on the results derived by the I-signal amplitude deriving unit 14I and the Q-signal amplitude deriving unit 14Q, and an averaging unit 18a which derives the gain imbalance GB by averaging the results derived by the carrier amplitude ratio deriving unit 16a.