Machine translation system, method and program for translating text having a structure

Machine translation system includes storage unit configured to store interpretation data items each including first expression element representing first expression of first language, word set element including first expression, and second expression element representing second expression of second language, first expression being to be translated into second expression, first expression and second expression belonging to category, acquiring unit configured to acquire predetermined expression of first language, predetermined expression being contained in to-be-translated text having structure, detecting unit configured to detect, from interpretation data items, interpretation data items each including expression element representing predetermined expression, selection unit configured to select, from detected interpretation data items, interpretation data item including word set element corresponding to same attribute or equivalent positional relationship in structure, and translation unit configured to translate predetermined expression into second language, using selected interpretation data item.