1. A structured illumination microscope device comprising: acquisition unit that repeats a series of processing including controlling a combination of a wave vector and a phase of fringes that spatially modulate a sample and successively acquiring N images related to the sample; computing unit that performs demodulation of an image of the sample using a required M types of images from an image set of consecutive P images updated upon acquisition of L of the images; the M types of images including: Q types (where Q≧3) of modulated images, the wave vectors thereof having a mutually closed relationship; and one type of modulated image having the wave vector in common with and the phase differing from at least one among the Q types of modulated images, or one unmodulated image; and an arrangement of the N images satisfying the following conditions: Uniformity condition: an intensity distribution of the fringes is spatially uniform when accumulated between the N images; and Refresh condition: the M types of images are always included in the image set.