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: 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.