An object detection apparatus acquires the value of an overlapping area which indicates a high probability that an object is located within a three dimensional space using data including a back projection of an object area on a three-dimensional space, acquires the integral quantity of the value of the overlapping area in a shape model including a three-dimensional target, and acquires the distribution degree of the value of the overlapping area in the shape model of the detection target. The apparatus further determines whether the inside of the shape model is an object or non-object using the integral quantity and the distribution degree.