1. An object detection apparatus comprising: a camera that is mounted to a vehicle and captures an image; an ECU configured to obtain a depth distance for each pixel area of the image based on the image; extract at least one potential object based on the depth distance; calculate an amount of change over time in the depth distance of the at least one potential object; and detect an object around the vehicle from among the at least one potential object using the amount of change over time; wherein when a first potential object and a second potential object that are adjacent in the image are extracted, and a second amount of change over time is twice a first amount of change over time, the second potential object is determined to be the same object as the first potential object, the first amount of change over time being the amount of change over time in the depth distance of the first potential object, and the second amount of change over time being the amount of change over time in the depth distance of the second potential object.