A needle direction estimation unit estimates a needle direction L based on needle information generated by a needle information generation unit, and outputs the position information of the needle direction L. A search region setting unit sets the needle direction L in a tissue image based on the position information of the needle direction L, and sets a search region F that extends to both sides with a predetermined width r. A needle tip search unit calculates the brightness distribution of the tissue image, determines a maximum brightness point B in the search region F to be the needle tip, and outputs the position information of the needle tip. A needle tip visualizing unit visualizes a needle tip N, which is a predetermined point image, in the tissue image from the position information of the needle tip.
