1. An image processing apparatus comprising: an image sensor, for acquiring a plurality of original images by imaging a specimen including a structure while changing a focal position of a microscope apparatus within an imaging range in an optical axis direction; an image analyzer, for obtaining information relating to the structure included in an image by applying image analysis processing to the image; and an image generator, for generating, on the basis of the plurality of original images, a first image to be used for the image analysis processing by said image analyzer and a second image to be used for visual observation by a user, wherein said image generator sets up a first depth range within the imaging range, the first depth range being narrower than the imaging range, selects only those original images whose focal positions are included within the first depth range out of the plurality of original images obtained from the specimen, and generates the first image using only the selected original images, and wherein said image generator sets up a second depth range within the imaging range, the second depth range being narrower than the first depth range, selects only those original images whose focal positions are included within the second depth range out of the plurality of original images obtained from the specimen, and generates the second image using only the selected original images.