A sample observation device includes: an emission optical system that emits planar light to a sample on an XZ plane; a scanning unit that scans the sample in a Y-axis direction so as to pass through an emission surface of the planar light; an imaging optical system that has an observation axis inclined with respect to the emission surface and forms an image of observation light generated in the sample; an image acquisition unit that acquires a plurality of pieces of XZ image data corresponding to an optical image of the observation light; and an image generation unit 8 that generates XY image data based on the plurality of pieces of XZ image data. The image generation unit extracts an analysis region of the plurality of pieces of XZ image data acquired in the Y-axis direction, integrates brightness values of at least the analysis region in a Z-axis direction to generate X image data, and combines the X image data in the Y-axis direction to generate the XY image data.