A threshold setting device, an object detection device, a threshold setting method, and a computer readable storage medium are shown. According to one implementation, the threshold setting device includes, an image acquisition unit, a ratio acquisition unit, and a setting unit. The image acquisition unit acquires an image including a specific object. The ratio acquisition unit acquires ratio information related to a ratio of a plurality of colors present in the specific object. The setting unit sets, based on the ratio information acquired by the ratio acquisition unit, a threshold used in a binarization process performed on the image including the specific object acquired by the image acquisition unit.