An object discrimination device includes an acquisition unit, a binarization unit, a feature extraction unit, and an area computation unit. The acquisition unit acquires an image of an imaging area where objects are aligned in an array from a direction orthogonal to the object alignment direction. The binarization unit generates, from the image, a binarized image of an object area that is an area where the object is present. The feature extraction unit computes a total pixel value for each array of pixel values aligned in a direction orthogonal to the object alignment direction in the binarized image, and generates a total pixel value array in which the total pixel values for the respective arrays are aligned in the object alignment direction. The area computation unit computes an object boundary in the alignment direction of the objects in the binarized image on the basis of the total pixel value array.