A non-linear microscope, comprising: a beam splitter splitting an optical path of an illuminating light (L1, L2) supplied from a light source into a pair of optical paths; a pair of deflecting mirrors (18, 21) individually deflecting the pair of optical paths toward mutually opposite sides of a specimen plane of a specimen; a pair of objective lenses (19, 20) individually disposed on the pair of optical paths and focusing on a common position on the specimen plane; a dichroic element disposed on a common part of the pair of optical paths and separating a coherent object light (Lr) from the illuminating light (L1, L2), the coherent object light (Lr) being occurred in a non-linear optical process at a focal point of the pair of objective lenses (19, 20); a detecting unit detecting the object light (Lr) separated by the dichroic element and generating a signal indicating light intensity at a light detecting part at which the object light (Lr) is detected; and a controlling unit repeatedly acquiring the signal generated by the detecting unit while scanning the specimen plane by the focal point and measuring a distribution of the signal on the specimen plane, characterized in that the dichroic element is a dichroic mirror, and in that the beam splitter is configured to be inserted into and removed from the optical path; and further comprising a first wavelength selection filter configured to be inserted into and removed from one of the pair of optical paths and cutting only the object light (Lr) among the illuminating light (L1, L2) directed toward the specimen plane and the object light (Lr) emitted from the specimen plane and a second wavelength selection filter configured to be inserted into and removed from the other of the pair of optical paths and cutting only the illuminating light (L1, L2) among the illuminating light (L1, L2) directed toward the specimen plane and the object light (Lr) emitted from the specimen plane. a beam splitter splitting an optical path of an illuminating light (L1, L2) supplied from a light source into a pair of optical paths; a pair of deflecting mirrors (18, 21) individually deflecting the pair of optical paths toward mutually opposite sides of a specimen plane of a specimen; a pair of objective lenses (19, 20) individually disposed on the pair of optical paths and focusing on a common position on the specimen plane; a dichroic element disposed on a common part of the pair of optical paths and separating a coherent object light (Lr) from the illuminating light (L1, L2), the coherent object light (Lr) being occurred in a non-linear optical process at a focal point of the pair of objective lenses (19, 20); a detecting unit detecting the object light (Lr) separated by the dichroic element and generating a signal indicating light intensity at a light detecting part at which the object light (Lr) is detected; and a controlling unit repeatedly acquiring the signal generated by the detecting unit while scanning the specimen plane by the focal point and measuring a distribution of the signal on the specimen plane, characterized in that the dichroic element is a dichroic mirror, and in that the beam splitter is configured to be inserted into and removed from the optical path; and further comprising a first wavelength selection filter configured to be inserted into and removed from one of the pair of optical paths and cutting only the object light (Lr) among the illuminating light (L1, L2) directed toward the specimen plane and the object light (Lr) emitted from the specimen plane and a second wavelength selection filter configured to be inserted into and removed from the other of the pair of optical paths and cutting only the illuminating light (L1, L2) among the illuminating light (L1, L2) directed toward the specimen plane and the object light (Lr) emitted from the specimen plane.