An azimuth calculation device includes: an acquiring unit configured to acquire signals of plural receiving antennas of an antenna group in which the plural receiving antennas are arranged in each of a first axis direction and a second axis direction, based on reception signals received by the antenna group; a first azimuth calculation unit configured to perform a calculation of a direction of arrival of radio wave in the first axis direction based on the signals of the plural receiving antennas acquired; a vector decomposition unit configured to perform vector decomposition with respect to each of antenna arrangement positions in the second axis direction using a result of the calculation by the first azimuth calculation unit; and a second azimuth calculation unit configured to perform a calculation of a direction of arrival of radio wave in the second axis direction, using a result of the vector decomposition.