1. A carotid-artery-plaque ultrasound-imaging method for producing an echo image of carotid artery plaque comprising: obtaining raw signals of echo signals corresponding to pixels that compose an echo image of carotid artery plaque, the echo signals being obtained when the echo image is obtained by a carotid artery echo integrated backscatter method, wherein said raw signals are integrated amounts per unit time of said echo signals; referencing the relationship between coloring ranges and colors, the available full range of the integrated amount being previously divided into the coloring ranges, and the colors being assigned to the coloring ranges, classifying the pixels, which are included in said obtained echo image, into the coloring ranges in accordance with the integrated amounts corresponding to the pixels, and coloring each of the pixels of the echo image in one of the colors corresponding to the range of the each of the pixels; displaying said colored echo image on a display; specifying an area on said colored echo image; correcting the raw signals of the echo image with a relative maximum value or a relative minimum value of a distribution of the raw signals in said specified area; coloring said echo image based on the corrected raw signals to obtain a corrected colored echo image, by referencing the relationship between coloring ranges and colors; and displaying the corrected colored echo image on the display.