Abstract: There is provided a pattern separation apparatus capable of separating patterns of a specific group from a plurality of patterns constituting a plurality of groups present in an n-dimensional pattern space in accordance with simple computational processing, the apparatus being used in a variety of applications such as recognition of characters, figures, and the like. An average of a set of patterns is calculated to be X.sub.av, and a vector closest to X.sub.av is defined as a key point and represented by X.sub.key, X.sub.key s chosen as the most central point. An n-dimensional space having X.sub.key as its center is assumed to calculate a main plane in which the number of patterns is larger than that of .largecircle. patterns. When other .largecircle. patterns are included in the main plane, a subplane is calculated to eliminate these patterns from the main plane. When other patterns are included in planes other than the main plane, a subplane for separating these patterns from the .largecircle.