Provided is a moisturizer having hygroscopicity and water retention ability, and also provided is a composition superior in antiseptic property and feeling on application, in addition to moisturizing property, and free of coloration and odorization. A moisturizer containing acylproline represented by the formula (1) wherein an acyl group represented by R 1 -CO- is an acyl group derived from a saturated or unsaturated fatty acid having 3 - 23 carbon atoms, or a salt thereof, and a composition containing (A) acylproline represented by the above formula (1) or a salt thereof and (B) bisphosphonate.
