PURPOSE: A method and an apparatus for estimating a DOA(Direction of Arrival Angle) of a coherent source are provided to remove a covariance matrix of unknown noise from an array structure without affecting signal components. CONSTITUTION: An array signal is received from an antenna(210) and a forward covariance matrix is obtained from the received signal(220). A backward covariance matrix is obtained from the received signal(230). A forward/backward spatial smoothing covariance matrix is obtained(240), and a difference between hermitians of a forward/backward spatial smoothing covariance matrix and a backward covariance matrix(250). The calculated matrix is decomposed by using an algorithm to estimate a direction angle and a vertical angle(260).