A machine translation system for translating a sentence of a first language to a sentence of a second language. The system has a dictionary, a display, an input unit, a selection data memory and a combination data memory. The translation possibilities for respective words and/or phrases of the original are obtained from the dictionary, ordered and are displayed by the display. The operator operates the input unit, thereby selecting one of the translation possibilities for each word or phrase. The selected possibilities for the words and phrases form a sentence of the second language, and are stored in the data memory in such a manner that they are associated with the equivalents of the first language. Further, the selected possibilities are stored in the combination data memory in such a way that any selected words or phrases that are semantically related are associated with the first language equivalent to one of the related words or phrases. The translation possibilities for any repeatedly used word or phrase of the first language are display in the priority order defined by the data stored in data memories.