An image processing apparatus (4) according to an aspect of the present invention includes a motion vector calculator (43) and an alignment processing unit (44). The motion vector calculator (43) calculates motion vector information between a fluorescence image of an observed region (S) based on fluorescence generated from the observed region (S) irradiated with excitation light, and a reflected-light image of the observed region (S) based on reflected light from the observed region (S). The alignment processing unit (44) corrects misalignment of an object between the fluorescence image and the reflected-light image of the observed region (S) based on the motion vector information.