To provide an ultrasonograph which outputs diagnostic information reflecting the state of complicated and delicate tissues accurately.

A vector setting part 402 for a processing object sets a position vector of a reference point selected at random on an attractor as an object vector. A neighbor vector searching part 403 searches for K of nearest neighbors and sets those position vectors. After a T step, a vector detecting part 404 detects position vectors after the T step (after a lapse of T hours) for the reference point and K of the nearest neighbors respectively. A translation vector arithmetic part 405 calculates translation vectors showing the amount of the movement after the T step for the reference point and the K of the nearest neighbors respectively. A translation error arithmetic part 406 calculates a translation error (vector dispersion) from the translation vector of the reference point and the translation vectors of K of the nearest neighbors.