An optical analyzer performing analysis excellent in spatial resolution and in invasion depth is provided. The analyzer includes a diagnostic light source section including a seed light source which outputs seed light, and a silica optical fiber to which seed light is input and which generates diagnostic light having a HE11 mode field pattern utilizing a nonlinear optical phenomenon, an irradiation optical system converging the diagnostic light and irradiating a measurement subject with the diagnostic light, an acquisition optical system acquiring object light generated at the measurement subject, a spectrum measurement section receiving the object light and measuring a frequency spectrum of the object light, a storage section storing information of a frequency spectrum of a known substance, and an arithmetic section calculating a correspondence between the frequency spectrum of the object light and the frequency spectrum of the known substance, and analyzing the measurement subject based on the calculation result.