1. An ultrasound diagnosis apparatus comprising: a change amount calculating unit configured to calculate amount of change of a pattern of each of a plurality of local regions among a plurality of ultrasound images generated along time series based on a reflected wave of an ultrasound wave transmitted by an ultrasound probe; an estimating unit configured to generate a position of a rotation axis of a scanning cross-section in each ultrasound image based on the amount of change of the pattern of each of the plurality of local regions calculated by the change amount calculating unit; and a display control unit configured to superimpose the rotation axis estimated by the estimating unit on each ultrasound image and display on a predetermined display unit.