A scanning microscope unit attached to a connection port (P1) of a microscope including a microscope optical system to constitute a scanning microscope, the scanning microscope unit comprising: a light source (10a-10d) configured to output irradiation light to a sample (M) to be observed; a photodetector (13a-13d) configured to detect observation light generated from the sample (M) in response to the irradiation light; a main housing ; a scan mirror in the main housing , the scan mirror being configured to scan the irradiation light output from the light source (10a-10d) on the sample (M) and guide the observation light generated from the sample (M) in response to the irradiation light to the photodetector (13a-13d); a scan lens configured to guide the irradiation light scanned by the scan mirror to the microscope optical system and to guide the observation light focused by the microscope optical system to the scan mirror ; a housing which constitutes a part of the main housing and to which the scan lens is fixed; an attachment portion which attaches the housing to the connection port (P1); and characterized in that the scanning microscope unit further comprises a movable portion which supports the housing so that an angle of the housing with respect to the attachment portion is changeable, wherein the outer surface of the movable portion and the inner surface of the housing are formed in a shape in which a center (C1) of a spherical surface including these shapes is located on an image plane (S1) of the microscope optical system of the microscope in a state in which the movable portion is fitted into the housing and the attachment portion is connected to the connection port (P1) of the microscope . a light source (10a-10d) configured to output irradiation light to a sample (M) to be observed; a photodetector (13a-13d) configured to detect observation light generated from the sample (M) in response to the irradiation light; a main housing ; a scan mirror in the main housing , the scan mirror being configured to scan the irradiation light output from the light source (10a-10d) on the sample (M) and guide the observation light generated from the sample (M) in response to the irradiation light to the photodetector (13a-13d); a scan lens configured to guide the irradiation light scanned by the scan mirror to the microscope optical system and to guide the observation light focused by the microscope optical system to the scan mirror ; a housing which constitutes a part of the main housing and to which the scan lens is fixed; an attachment portion which attaches the housing to the connection port (P1); and characterized in that the scanning microscope unit further comprises a movable portion which supports the housing so that an angle of the housing with respect to the attachment portion is changeable, wherein the outer surface of the movable portion and the inner surface of the housing are formed in a shape in which a center (C1) of a spherical surface including these shapes is located on an image plane (S1) of the microscope optical system of the microscope in a state in which the movable portion is fitted into the housing and the attachment portion is connected to the connection port (P1) of the microscope . <EOS>