1. An ultrasound diagnosis apparatus, comprising: an image generator configured to execute transmission and reception of ultrasound waves to chronologically generate ultrasound image data of plural frames; a multiresolution decomposition part configured to hierarchically execute multiresolution decomposition on the ultrasound image data of plural frames to obtain first-order to n th -order (n represents a natural number of 2 or more) low-band decomposition image data and first-order to n th -order high-band decomposition image data; a feature amount calculator configured to calculate a feature amount based on the obtained low-band decomposition image data; a filtering processor configured to execute a filter operation on the calculated feature amount of ultrasound image data which becomes a filtering processing object based on a feature amount calculated by ultrasound image data of plural frames imaged at time prior to a time at which a frame of the ultrasound image data is imaged; and a multiresolution composition part configured to execute multiresolution composition by using the low-band decomposition image data and the high-band decomposition image data to generate a composite image.