1. An ultrasound imaging device that images an ultrasound image, comprising: an ultrasound transceiver configured to irradiates an ultrasound wave to a subject and receives a reflected signal; a blood flow detection unit configured to detects a blood flow velocity in the subject using the reflected signal; and a shape recognition unit configured to recognize a tissue shape of the subject using the reflected signal; wherein the blood flow detection unit is configured to: remove an image portion indicating a tissue shape of the subject based on a plurality of ultrasound images of the subject created by using the reflected signal at different times, calculate a blood flow velocity vector in the subject based on a plurality of images at different times in which the image portion indicating the tissue shape of the subject is removed, identify a boundary surface between a tissue of the subject and a blood flow based on a recognition result of the shape recognition unit, and calculate or correct the blood flow velocity by applying a consistent condition under a fluid mechanics on the boundary surface.