A cell-image acquisition device includes: a stage supporting a vessel containing a cell and a culture fluid; a light source emitting illumination light; a focusing lens disposed below the stage and focusing, when the illumination light is made to enter from above a liquid surface of the culture fluid, light transmitted through the vessel; an aperture disposed so as to block part of the focused light; an image acquisition element acquiring an image of light passing through the aperture and having pixels arrayed in a straight line; a movement mechanism including guide rails and a motor and moving the light source, the focusing lens, the aperture, and the image acquisition element, relative to the stage, in a horizontal direction perpendicular to an array direction of the pixels; and a controller adjusting an incident angle of the illumination light on the liquid surface, about an axis parallel to the array direction.