1. An object detection device, comprising: an image recognition unit configured to detect an object being recognized in an input frame image, and identify a position of a detected object which is detected as the object being recognized in the input frame image; a storage unit configured to store a position of a first past detected object which is detected as the object being recognized in a first past frame image which is input immediately before the input frame image; a distance calculation unit configured to calculate a first distance from the position of the first past detected object to the position of the detected object which is detected in the input frame image; and a first determination unit configured to determine that the detected object which is detected in the input frame image is identical to the first past detected object if the first distance is smaller than a first reference distance which is previously set.