1. An image processing apparatus comprising a processor executing a program recorded on a memory device, the executed program performing functions of: an object detection unit configured to detect an object area corresponding to an object from an image by using a first method; a tracking unit configured to track the detected object; a trajectory management unit configured to manage a trajectory of the object being tracked; a specific object detection unit configured to detect a specific object area corresponding to a specific object having a specific character or a specific pattern from the image by using a second method capable of detecting the specific object area without using a result of detection by the first method; and an object association unit configured to determine, based on a size of a crossover between the object area detected by the object detection unit by using the first method on the image and the specific object area detected by the specific object detection unit by using the second method on the image, whether to associate the object detected by the object detection unit and the specific object detected by the specific object detection unit, wherein the trajectory management unit stores data indicating that the object detected by the object detection unit and the specific object detected by the specific object detection unit are associated with each other by the object association unit.