1. In a machine translation system translating a source language into a target language, a translation support method comprising the steps of: reading a source language text; dividing said text into words; extracting, from sequential said words from said dividing step, sequential word groups which occur a plurality of times throughout said text; displaying ones of extracted said sequential word groups satisfying a predetermined occurrence frequency, as complex word candidates; and allowing user selection of at least one complex word candidate of said complex word candidates, to be treated as a complex word which is to be translated as an integral complex word.