An observation apparatus compares a plurality of image information acquired in a specific time by a plurality of image acquisition methods whose image acquisition timings are different, and includes a timer for counting observation time, and a PMT and a CCD whose image information acquisition timings are different. A storage unit stores different image information, when acquired by the PMT and the CCD, by relating each type of the acquired image information to the observation information counted by the timer. A control unit sets a display standard to associate the different types of image information stored in the storage unit, according to the observation time that has been respectively related to these types of image information, and associates the different types of image information according to the time information, on the basis of the set display standard. A monitor displays the image information associated by the control unit.