Aqueous preservative solutions with a high amino acid content which is excellent in preservation, particularly a preservative effect on fungi, and safety, and is excellent in storage stability so as not to cause a problem such as depositing, coloring or smelling even when it is stored for a long time, and when incorporated in a cosmetic, is capable of imparting a high moisturizing effect without causing a sticky feeling, and imparting an effect of preventing dyed hair from color fading, can be achieved by incorporating pyrrolidone carboxylic acid and/or a salt thereof (Component A), a basic amino acid and/or a salt thereof (Component B), an acidic amino acid and/or a salt thereof (Component C), a neutral amino acid and/or a salt thereof (Component D) and lactic acid and/or a salt thereof (Component E) at a specific incorporation ratio and at a specific pH.
