The observing apparatus is being equipped with an image-forming optical system which forms an image of light emitted from a specimen, an imaging unit which picks up the image of the specimen formed by the image-forming optical system, and an illuminating unit which illuminates the specimen with a surface illuminant in which bright areas and dark areas are arranged alternately in order to provide an observing apparatus suitable to observe a transparent specimen with a wide field of view. If the position of the surface illuminant and the pitch of contrasting are set properly, each partial area of the specimen is illuminated obliquely at a small angle by each bright area of the surface illuminant. Therefore, the imaging unit can acquire a dark-field observation image of each partial area.