In the traditional theory of consumer's behavior, circulating money is nonexistent. It is the numeraire that plays a role in it. The reason Why the l traditional theory excludes circulating money is that money has no direct utility. This is quite true under static conditions, in the strictest sense, but we can recognize direct utility in holding money, if we develop the problem under the looser static conditions in the point that they contain some assumptions as to 'time'. So, in this paper, we are engaged in modifying the traditional theory so as to be able to describe the consumer's behavior in the case where the consumer demands not only commodities but money. We begin with setting necessary assumptions and explaining what sort of satisfaction the consumer derives from holding money under those assumptions. Then we proceed to introduce money into utility function. Both C.E.V. Leser and P. A. Samuelson introduce money into utility function in the form of purchasing power over each kind of commodity. But we choose the way of introducing money into it in the form of purchasing power over the commoditiy-in-general. Our method enables us to obtain the same results more easily than they did. These results are as follows. (1) Slutsky equation should be modified so as to include two new terms besides two ordinary income and substitution terms. The two terms measure indirect income, and indirect substitution, effect. (2) Between the γth commodity and the sth one, we can not say that the substituion effect on the γth commodity resulting from a change in the sth price is the same as the substitution effect on the sth commodity resulting from a change in the γth price. This fact is due to the existence of the indirect substitution effect. (3) Consumer's income remaining unchanged, an equi-proportionate change in all price has only an income, and not substitution, effect. (4) If consumer's income changes in the same proportion as all prices, the real condition of consumer's demand remains unchanged. Accordingly, in this case, the fundamental proposition of the Quantity Theory of money holds true ; the elasticity of demand for money is unity.