An image processing apparatus acquires a plurality of pieces of first image data generated using volume data that is based on acoustic waves, extracts feature points from a plurality of pieces of the first image data, sets an unnecessary region to one or a plurality of pieces of the first image data using a distribution of the extracted feature points, reduces pixel values of the unnecessary region in one or a plurality of pieces of the first image data to which the unnecessary region has been set, and generates second image data using one or a plurality of pieces of the first image data in which the pixel values of the unnecessary region have been reduced and one or a plurality of pieces of the first image data in which the unnecessary region is not included.