To prepare a cosmetic which contains alkali ion water obtained by an electrolysis treatment, little causes the deterioration of pH value with the passage of time, and thereby stably exhibits various efficacies originated from the alkali ion water, such as moisture retainability and cleansability, over a long period.

This cosmetic containing silicone compound-containing alkali ion water produced on the side of a cathode on the application of an electrolysis treatment to raw material water containing a silicone compound-containing material is characterized in that the silicone compound-containing alkali ion water exhibits an alkaline property having a pH value of 7.1 to 13.0 and that the cosmetic contains the silicone compound specified according to JIS K 0101 in an amount of 0.1 to 300 mg/L.