A structured illumination microscope, comprising: a spatial light modulator using ferroelectric liquid crystals, an interference optical system for illuminating a specimen with an interference fringe generated by causing lights from the spatial light modulator to interfere with each other, a controller for applying a voltage pattern having a predetermined voltage value distribution to the spatial light modulator, an image forming optical system for forming an image of the specimen, which has been irradiated with the interference fringe, an imaging element for generating an image by imaging the image formed by the image forming optical system, and a demodulating part for generating a demodulated image using a plurality of images, wherein the controller applies a plurality of image generation voltage patterns for generating the demodulated images and a burn-in prevention voltage pattern for preventing a burn-in of the light modulating part, characterized in that: the burn-in prevention voltage pattern is based on a reverse voltage of a sum voltage pattern that is a sum of the plurality of the image generation voltage patterns; and a time during which the burn-in prevention voltage pattern (A'; B'; C') is applied is shorter than a sum time that is a sum of times during which the plurality of image generation voltage patterns (A 1, A 2, A 3, A 4, A 5; B 1, B 2, B 3, B 4, B 5; C 1, C 2, C 3, C 4, C 5) is applied. a spatial light modulator using ferroelectric liquid crystals, an interference optical system for illuminating a specimen with an interference fringe generated by causing lights from the spatial light modulator to interfere with each other, a controller for applying a voltage pattern having a predetermined voltage value distribution to the spatial light modulator, an image forming optical system for forming an image of the specimen, which has been irradiated with the interference fringe, an imaging element for generating an image by imaging the image formed by the image forming optical system, and a demodulating part for generating a demodulated image using a plurality of images, wherein the controller applies a plurality of image generation voltage patterns for generating the demodulated images and a burn-in prevention voltage pattern for preventing a burn-in of the light modulating part, characterized in that: the burn-in prevention voltage pattern is based on a reverse voltage of a sum voltage pattern that is a sum of the plurality of the image generation voltage patterns; and a time during which the burn-in prevention voltage pattern (A'; B'; C') is applied is shorter than a sum time that is a sum of times during which the plurality of image generation voltage patterns (A 1, A 2, A 3, A 4, A 5; B 1, B 2, B 3, B 4, B 5; C 1, C 2, C 3, C 4, C 5) is applied. the burn-in prevention voltage pattern is based on a reverse voltage of a sum voltage pattern that is a sum of the plurality of the image generation voltage patterns; and a time during which the burn-in prevention voltage pattern (A'; B'; C') is applied is shorter than a sum time that is a sum of times during which the plurality of image generation voltage patterns (A 1, A 2, A 3, A 4, A 5; B 1, B 2, B 3, B 4, B 5; C 1, C 2, C 3, C 4, C 5) is applied.