The present invention provides an object measuring apparatus capable of performing high-speed process and accurately counting the number of a plurality of objects even in the case where the plurality of objects pass a boundary line simultaneously. The object measuring apparatus extracts motion vectors at a plurality of times in each of a plurality of positions on a boundary line on the basis of a plurality of images. The object measuring apparatus obtains at least one integral value by integrating components perpendicular to the boundary line of the motion vectors. As the at least one integral value, for example, an integral value derived by integrating the perpendicular components of one of positive and negative signs is obtained. The object measuring apparatus calculates the number of moving objects (people and the like) passing the boundary line on the basis of the integral value.