The present invention relates to An N-acetylglucosamine derivative represented by the following formula (1), and a hyaluronic acid production promoting agent containing the same and a skin external preparation containing the same: ##STR00001## wherein R.sup.1 is a hydrogen atom or an alkyl group having 2 to 18 carbon atoms; R.sup.2, R.sup.3, and R.sup.4 are hydrogen atoms or acyl groups having 2 to 18 carbon atoms and may be all the same or different from others; the steric structure at position 1 may be .alpha. or .beta.; provided that R.sup.1, R.sup.2, R.sup.3, and R.sup.4 must not be all hydrogen atoms.It is intended to provide an easily available hyaluronic acid production promoting agent and a skin external preparation whereby the production of hyaluronic acid can be promoted in the skin and thus the skin can be maintained in a vital and moist state so that it is expected that the human skin can be prevented from age.