A phonetic distance calculation method for similarity comparison between phonetic transcriptions of foreign words. A system manager defines character element transformation patterns occurrable between phonetic transcriptions derived from the same foreign language. A system generates new phonetic transcriptions according to the defined character element transformation patterns and assigns a demerit mark to each of the generated phonetic transcriptions according to a phonetic distance. A minimum phonetic distance between each of the generated phonetic transcriptions and a given phonetic transcription is calculated on the basis of a minimum edit distance calculation method. Any one of the generated phonetic transcriptions with a smallest one of the calculated minimum phonetic distances is determined to be most similar to the given phonetic transcription. Therefore, a document retrieval operation can accurately be performed in a document retrieval system and a document retrieval time can be reduced therein, resulting in a significant improvement in the performance of the document retrieval system.