The present invention relates to an ultrasound imaging device. The ultrasound imaging device includes: a data acquiring unit for acquiring 3-dimensional ultrasound image data based on receive signals formed based on ultrasound echoes reflected from a target object; a filtering unit for determining a size of a filtering mask of a filter, said size being adaptively determined according to an amount of the 3-dimensional ultrasound image data in data acquisition directions, the filtering unit being further configured to filter the 3-dimensional ultrasound image data by using the filtering mask; a scan converting unit for scan-converting the filtered 3-dimensional ultrasound image data; and a 3-dimensional rendering unit for performing 3-dimensional rendering upon the scan-converted 3-dimensional ultrasound image data to form a 3-dimensional ultrasound image.