1. An imaging apparatus for diagnosis comprising: a probe which accommodates an imaging core that performs transmission and reception of a signal; a generation unit which repeats the transmission and reception of a signal with respect to an imaging target object and generates a tomographic image of the imaging target object; and a detection unit which detects 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.