In this contribution, we propose a DOA (Direction Of Arrival) estimation method of speech signal whose angular resolution is almost uniform with respect to DOA. Our previous DOA estimation method[1] achieves high precision with only two microphones, however its resolution degrades as the propagating direction apart from the array broadside. In the proposed method, the equilateral-triangular microphone array is adopted, and the subspace analysis is applied. The efficiency of the proposed method is shown both from the simulation and experimental results.