A direction finder (1) is provided with: an antenna device (10) for outputting N-system analog input signals in parallel; a signal-synthesizing unit (21) for synthesizing the N-system analog input signals to thereby cause the signals to mutually interfere; a band selection unit (22) for selectively outputting signal components in a passband among the outputs of the signal-synthesizing unit (21); an A/D conversion unit (23) for digitizing the output of the band selection unit (22); a data storage unit (25) for saving a database in which a correspondence between the frequency characteristics of an radio wave and the direction of arrival of the radio waves is established; a control unit (26) for controlling the band selection unit (22) to change the passband; and a direction of arrival estimation unit (24). The direction of arrival estimation unit (24) calculates the frequency characteristics of the output of the A/D conversion unit (23) and verifies the calculated frequency characteristics with the database to thereby estimate the direction of arrival of received radio waves.
