A modified hyaluronic acid and/or a salt thereof comprises a glycerin skeleton-containing group shown by the following general formula (1), €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ-O-CH 2 -CHOH-CH 2 -OR 1 €ƒ€ƒ€ƒ€ƒ€ƒ(1) wherein, R 1 represents a linear or branched alkyl group, or a linear or branched alkenyl group.