1. An odor measuring apparatus, comprising: a) m pieces of odor sensors having different responsive characteristics, where m is an integer greater than one; b) an angle calculator for calculating an angle between an unknown odor vector and a standard odor vector in an m-dimensional space formed by a result of a measurement with the m pieces of odor sensors, where the unknown odor vector is represented by a result of a measurement of an unknown sample and the standard odor vector is represented by a result of a measurement of a known standard odor; and c) an index calculator for calculating an index that represents a similarity of the unknown odor to the standard odor, where the index is calculated based on said angle.