1. An imaging apparatus for diagnosis comprising: a probe which accommodates an imaging core configured to perform transmission and reception of a signal; a generation unit configured to repeat the transmission and reception of a signal with respect to an imaging target object and generate a tomographic image of the imaging target object; a detection unit configured to detect a low luminance region, of which a pixel value is comparatively lower than a pixel value around the low luminance region, as a detection target region, by performing a morphological operation in the tomographic image; and wherein the generation unit is configured to repeat processing of obtaining black hat images by aligning line data for generating the tomographic image of the imaging target object in parallel, set the direction of the structural element to a direction of the line data, and change the length of the structural element, within a range up to the maximum display radius, and obtain a black hat-totalized image by adding the obtained black hat images together.