An ultrasonic diagnostic apparatus includes: a first reference beam generating unit generating a first reference beam from DAS signals calculated in an N-th frame; a second reference beam generating unit generating a second reference beam from a DAS signal calculated in an (N−1)-th frame, the DAS signal calculated in the N-th frame, and another DAS signal calculated in an (N+1)-th frame; an attenuation coefficient calculating unit calculating, based on the first reference beam and the second reference beam, an attenuation coefficient to be multiplied by the DAS signals calculated in the N-th frame; and a beamforming unit generating and providing a beamformed signal generated for a reference scan line in the N-th frame by multiplying a DAS signal calculated in the N-th frame by the attenuation coefficient.