In an ultrasound diagnosis apparatus, a plurality of transducers arranged in an ultrasound probe are classified into two transducer groups. By using a parallel simultaneous reception method, ultrasound beams from an observation point of an object to be examined along a transmitting direction of an ultrasound beam are received by the transducer groups. In other words, echo signals from different directions at the observation point are received. Flow velocities are respectively calculated on the basis of the echo signals received by the transducer groups, and the calculated flow velocities are added and averaged.