An ultrasound diagnostic device including a component specifier. Assume a first direction is a depth direction substantially perpendicular to a surface of a subject, a second direction is a direction orthogonal to the first direction, a first pixel is a pixel at a pixel location N in the second direction, a second pixel is a pixel at a pixel location N+1 in the second direction, and N is a positive integer. The component specifier detects one or more feature lines from the ultrasound image by repeatedly, while incrementing N, linking the first pixel with the second pixel when luminance of the second pixel is high and the second pixel is in close proximity to the first pixel, and specifies which of the one or more feature lines indicates a boundary between components, based on an order in the first direction of the one or more feature lines.
