J.S. Mill's theory of meaning seems to be opposite to ones which leads us to philosophical solipcism. This can be seen apparently in his statement: 'What does any one's personal knowledge of things amount to, after subtracting all which he has acquired by means of the words of other people?' He insists, 'Names are names of things, not of our ideas of them'. According to him, terms can be devided into two types: nonconnotative names and connotative names. All names (terms) are names of something, i.e. denote something. A connotative term 'connotes', i.e. 'implies' or 'means' an attribute or a set of attributes of the thing denoted by the term, while he says that nonconnotative names have no connotation and therefore no meaning. For Mill, meaning of a term is its connotation, i.e. an attribute or a set of attributes of the thing denoted by the term, something objective, not something mental. I think we can say that Mill's intention in his System of Logic is to depsychologize the theory of meaning, though whether he has succeeded in it is problematic. In this paper, I would like to clarify his theory of meaning, in which 'denotation' and 'connotation' play important roles, and criticise it, sometimes referring to other philosophers like Husserl and Wittgenstein.