1. An ultrasound imaging device that images an ultrasound image, comprising: an ultrasound transceiver that irradiates an ultrasound wave to a subject and receives a reflected signal; and a blood flow detection unit that detects a blood flow velocity in the subject using the reflected signal; wherein the blood flow detection unit removes an image 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, and calculates a blood flow velocity vector in the subject based on a plurality of images at different times in which the image indicating the tissue shape of the subject is removed.