An image processor according to the present invention is configured to generate a plurality of multiresolution images of different resolutions from an input image (S16), to set a correlation evaluation function for each multiresolution image, calculate a correlation value between the correlation evaluation function and each pixel in the multiresolution image, and extract a position of a local region on the basis of the correlation value (S18), and to set a size of the local region according to the resolution of the multiresolution image (S22), and to detect an object in the local region. This enables extraction of the local region at an appropriate position and in an appropriate range for a characteristic portion of the input image. For this reason, a target range is appropriately limited and detection of the object is quickly carried out without deterioration of accuracy.