Provided is an in vivo movement tracking apparatus configured to track a portion of interest that moves in vivo, in which accuracy and robustness of tracking are improved. The apparatus is configured to determine an estimated position of ah organ in a biological image based on the past movement of the organ and search for contour points corresponding to a plurality of control points, respectively, representing a contour shape of the organ in a region corresponding to the estimated position, to thereby determine an estimated contour of the organ based on the contour points. The in vivo movement tracking apparatus is configured to determine a position of a portion of interest, which moves in association with the organ, based on the estimated contour with reference to previously acquired sample data regarding a positional relationship between a contour of the organ and the portion of interest.
