A confocal microscope unit attached to a connection port of a microscope including a microscope optical system to constitute a confocal microscope, the confocal microscope unit comprising: a first subunit including a light source configured to output first excitation light, a first aperture configured to limit a luminous flux of first fluorescence generated from a sample to be observed in response to the first excitation light, and a first photodetector configured to detect the first fluorescence having passed through the first aperture; a second subunit including a light source configured to output second excitation light, a second aperture configured to limit a luminous flux of second fluorescence generated from the sample in response to the second excitation light, and a second photodetector configured to detect the second fluorescence having passed through the second aperture; a scan mirror configured to scan the excitation light output from the first and second subunits (6a, 6b) on the sample and guide the fluorescence generated from the sample in response to the excitation light to the first and second subunits (6a, 6b); a scan lens configured to guide the excitation light scanned by the scan mirror to the microscope optical system and to guide the fluorescence focused by the microscope optical system to the scan mirror; and a main housing which is formed to be attachable to the connection port and to which the scan mirror, the scan lens, the first subunit, and the second subunit are fixed, characterised in that the first subunit includes a first beam splitter configured to reflect the first excitation light and the first fluorescence and transmit the second excitation light and the second fluorescence, wherein the light source outputting the first excitation light, the first aperture, the first photodetector, and the first beam splitter included in the first subunit, are disposed on a first base plate in the main housing and wherein the light source outputting the second excitation light, the second aperture, and the second photodetector included in the second subunit, are disposed on a second base plate in the main housing. a first subunit including a light source configured to output first excitation light, a first aperture configured to limit a luminous flux of first fluorescence generated from a sample to be observed in response to the first excitation light, and a first photodetector configured to detect the first fluorescence having passed through the first aperture; a second subunit including a light source configured to output second excitation light, a second aperture configured to limit a luminous flux of second fluorescence generated from the sample in response to the second excitation light, and a second photodetector configured to detect the second fluorescence having passed through the second aperture; a scan mirror configured to scan the excitation light output from the first and second subunits (6a, 6b) on the sample and guide the fluorescence generated from the sample in response to the excitation light to the first and second subunits (6a, 6b); a scan lens configured to guide the excitation light scanned by the scan mirror to the microscope optical system and to guide the fluorescence focused by the microscope optical system to the scan mirror; and a main housing which is formed to be attachable to the connection port and to which the scan mirror, the scan lens, the first subunit, and the second subunit are fixed, characterised in that the first subunit includes a first beam splitter configured to reflect the first excitation light and the first fluorescence and transmit the second excitation light and the second fluorescence, wherein the light source outputting the first excitation light, the first aperture, the first photodetector, and the first beam splitter included in the first subunit, are disposed on a first base plate in the main housing and wherein the light source outputting the second excitation light, the second aperture, and the second photodetector included in the second subunit, are disposed on a second base plate in the main housing.