An image acquisition section of an information processor acquires stereo images from an imaging device. An input information acquisition section acquires an instruction input from a user. A depth image acquisition portion of a position information generation section generates a depth image representing a position distribution of subjects existing in the field of view of the imaging device in the depth direction using stereo images. A matching portion adjusts the size of a reference template image in accordance with the position of each of the subjects in the depth direction represented by the depth image first, then performs template matching on the depth image, thus identifying the position of a target having a given shape and size in the three-dimensional space. An output information generation section generates output information by performing necessary processes based on the target position.