An image processor (24) of an endoscope apparatus (10) generates an intermediate emphasis image that is an image in which the degree of emphasis of the diagnosis target substance is intermediate with respect to an emphasis image that is an image generated from emphasis image signals and a non-emphasis image that is an image generated from non-emphasis image signals, based on the emphasis image signals that are imaging signals for the reflected and scattered light (RL) of the illumination light (IL) including rays of emphasis narrowband light that is light in emphasis wavelength ranges that allows the diagnosis target substance existing in the observation object O to be emphasized and observed, and the non-emphasis image signals that are imaging signals for the reflected and scattered light of the illumination light including non-emphasis narrowband light that is light in non-emphasis wavelength ranges not including the emphasis wavelength ranges.
