1. An object recognition apparatus, comprising: an input section for inputting a first image set including a predetermined number of images including a first image representing a first target object using a first attribute and a second image representing the first target object using a second attribute different from the first attribute, wherein the predetermined number is two or more; a feature vector calculation section for calculating a first feature vector in a feature space having at least one filter output value as a vector component, the at least one filter output value being obtained by applying at least one predetermined image filter to at least one predetermined position in the predetermined number of images in the first image set; and a judgment section for judging whether or not the first target object is categorized into a specific category based on a relationship between the first feature vector and predetermined discriminant parameters.