The aim of this paper is to analyze the grammatical status of English core negative element ne and not in the process of diachronic changes. Negation was generally expressed by the negative particle ne throughout OE. It came to be expressed by the weakened ne in combination with the negative adverb not in ME, and as ne disappeared, not started to be used exclusively from around the fifteenth century. There was a temporary tendency to place not before a lexical verb until the verb do became fully grammaticalized as an auxiliary, but negation began to be derived with the syntactic structure of `a finite modal verb/do＋not＋a lexical verb` from the later period of Early ModE. Contracted negation came to be optionally expressed through negative contraction in terms of encliticization of not to the preceding finite verb from Late ModE.