1. A programming language processing system for use as a computer language processing system wherein a program described in a high level programming language is translated into a program written in a low level programming language, comprising: means for inputting a program described according to a specification of a programming language in which basic words are classified by parts-of-speech including nouns, adjectives, conjunctions, and logic words; processing means for converting said program described according to said specification into an internal expression form based on a sentence structure of a type that can be converted to a binary tree, and for converting a logical meaning expressed by said internal expression form, according to program logic for term-rewriting based on pattern collation, to a low level program description in which said parts-of-speech are deleted.