1. A character recognition system for performing character recognition by comparing distances between a feature vector extracted from an input pattern and reference vectors of previously stored target characters, wherein all characters are classified into plurality of classes based on occurrence frequencies of the target characters, a dictionary storage device for storing the reference vectors for each of the classes and a computer are included, and the computer is programmed to calculate distances between the feature vector and the reference vectors of plurality of characters belonging to a class having a highest character occurrence frequency among the plurality of classes, and to select, when there is a distance smaller than a class threshold determined for the class, a character of a reference vector corresponding to the distance as a character candidate.