A pre-edit support method for a machine translation system has an improved accuracy of parsing and an improved efficiency of pre-edit support. In a machine translation system translating a source language into a target language, a source language text is read and divided into words. Word sequences occurring a plurality of times are extracted, of the extracted word sequences the word sequences having a high occurrence frequency or a large number/high ratio of words with multiple parts of speech, are extracted as complex word candidates and displayed to a user, of the complex word candidates the complex word candidates the user designates are used as complex words to be translated integrally, and pre-edit symbols are added to the integral complex words as translation support information.