An ultrasound probe comprising: a transducer configured to receive an echo ultrasound signal by emitting a plane wave at least four times (P1, P2, P3, P4) at emission angles which are dependent on each other; and a probe controller configured to obtain an ultrasound image by determining at least four Doppler shift frequencies from the received echo ultrasound signal and calculating at least one of a speed of an object (ob) and a speed of the object (ob) in each of directions on the basis of the determined Doppler shift frequency and the dependent emission angles, wherein the dependent emission angles are represented by two angle parameters, wherein one of the two angle parameters of each of the dependent emission angles is set to be the same as one of the two angle parameters of the other emission angles, and the other angle parameter of each of the dependent emission angles is set to be spaced apart from the other angle parameters of the other emission angles according to a predetermined angle, wherein the probe controller controls the transducer to emit the plane wave at least four times (P1, P2, P3, P4) at the dependent emission angles, determines at least four Doppler shift frequencies from the echo ultrasound signal received by emitting the plane wave at least four times (P1, P2, P3, P4), determines a blood flow speed of the object (ob) in each of the directions on the basis of the determined at least four Doppler shift frequencies and the dependent emission angles and obtains information regarding a blood flow speed of the object (ob) on the basis of the blood flow speed of the object (ob) in each of the directions. a transducer configured to receive an echo ultrasound signal by emitting a plane wave at least four times (P1, P2, P3, P4) at emission angles which are dependent on each other; and a probe controller configured to obtain an ultrasound image by determining at least four Doppler shift frequencies from the received echo ultrasound signal and calculating at least one of a speed of an object (ob) and a speed of the object (ob) in each of directions on the basis of the determined Doppler shift frequency and the dependent emission angles, wherein the dependent emission angles are represented by two angle parameters, wherein one of the two angle parameters of each of the dependent emission angles is set to be the same as one of the two angle parameters of the other emission angles, and the other angle parameter of each of the dependent emission angles is set to be spaced apart from the other angle parameters of the other emission angles according to a predetermined angle, wherein the probe controller controls the transducer to emit the plane wave at least four times (P1, P2, P3, P4) at the dependent emission angles, determines at least four Doppler shift frequencies from the echo ultrasound signal received by emitting the plane wave at least four times (P1, P2, P3, P4), determines a blood flow speed of the object (ob) in each of the directions on the basis of the determined at least four Doppler shift frequencies and the dependent emission angles and obtains information regarding a blood flow speed of the object (ob) on the basis of the blood flow speed of the object (ob) in each of the directions. <EOS>