An object detection device of an object detection system includes an object detection determination unit including a bird candidate determination unit for determining, from an image acquired by imaging a moving object, whether or not the moving object is a specific detection subject (bird in this case), and a bird type/attitude estimation unit for estimating, based on a contour of the moving object determined to be the bird by the bird candidate determination unit and a WFM library storing contour shape information, which is a contour prepared for each of types of the specific detection subject (types of the bird in this case), a type of the moving object out of the types of the specific detection subject.