Minoxidil preparations having a sustained action by which a fully satisfactory effect of stimulating hair growth can be obtained when applied once a day. Namely, hair growth stimulant compositions with a sustained action, which comprise (A) 2 to 6% by mass of minoxidil and (B) 5 to 30% by mass of a mixture of 1,3-butylene glycol or dipropylene glycol with glycerol blended at a weight ratio of 10:1 to 1:4, exert an excellent effect of stimulating hair growth.