1. A machine translation system (FIG. 7) which generates sentences in target language using tree structure expression in source language comprising; a pattern dictionary (PTD, FIG. 7) for storing a table of target language and source language, means (PPD, FIG. 7) having at least a first shift register (PPA) having source tree patterns from said pattern dictionary, a second shift register (PPB) having source tree which is to be translated, a coincidence detector (CSD) for comparing outputs of said first (PPA) and second (PPB) shift registers; for providing coincident pattern of patterns contained in the pattern dictionary and partial pattern of tree structure in source language including the topmost mode of said tree structure; means (SDS, FIG. 7) for producing a pattern in said target language and an instruction to lower layer utilizing the information of information from instruction from upper layer, extraction information (EXG, FIG. 7), and production rule (stored in PRT, FIG. 7) peculiar to said coincident pattern; means (INA, MPE, FIG. 7) having a first shift register (AAA) storing said instruction to lower layer, a second shift register (AAB) storing said tree structure, AND-OR logic means for coupling the output of said first shift register (AAA) to the output of said second shift register (AAB) to eliminate said coincident pattern; means (SPC, FIG. 7) having a first shift register (UAA) storing separated partial target trees, a second arithmetic register (UAB) for performing operation to signal in said first shift register (UAA), and a third shift register (UAC) for storing the output of said second register (UAB), so as to produce a final target language tree which is connected to the result of said partial target tree through repeating said means (SPC) until the whole of said tree structure is eliminated; and means (SPL, FIG. 7) for receiving the output of said SPC means and generating final sentence in target language.