A scanning optical microscope comprising a laser source, a scan optical system for scanning a sample with a laser beam from the laser source, a spectral resolving optical system for resolving spectra of fluorescent rays from the sample, a wavelength splitting optical system for splitting the fluorescent rays that have passed the spectral resolving optical system into rays of a plurality of different wavelengths and guiding the split rays to optical paths of the plurality of different wavelengths, a plurality of image forming optical systems, respectively provided in the optical paths of the plurality of different wavelengths, for forming images of the fluorescent rays from the sample, a plurality of confocal apertures respectively provided in the optical paths at focal points of the image forming optical systems, and a plurality of photosensors, respectively provided in the optical paths, for sensing the fluorescent rays from the sample that have passed the respective confocal apertures.