In this paper, we describe a method for automatically retrieving collocations from large text corpora. This method retrieve collocations in the following stages: 1) extracting strings of characters as units of collocations 2) extracting recurrent combinations of strings in accordance with their word order in a corpus as collocations. Through the method, various range of collocations, especially domain specific collocations, are retrieved. The method is practical because it uses plain texts without any information dependent on a language such as lexical knowledge and parts of speech.