1. A machine translation apparatus comprising: a central processing unit; an identification information detection unit that detects, from a designated physical object or an attachment thereto, identification information of the designated object; a receiving unit that receives a source language sentence; a word dividing unit that divides the source language sentence into a plurality of first words by morphological analysis; a deixis detection unit that detects, from the first words, a deixis indicating the designated object; a correspondence setting unit that sets a correspondence between the identification information of the designated object and the deixis; a semantic class determining unit executing on the central processing unit that determines a semantic class indicating a semantic attribute of the designated object previously associated with the identification information of the designated object; and a translation unit that translates the source language sentence according to the determined semantic class of the designated object corresponding to the deixis.