Provided is a means for exhibiting an excellent fucoidan effect by developing a new method for administering a fucoidan-containing hair growth agent. This hair growth agent is characterized by being formed from a combination of a fucoidan-containing microneedle, and a fucoidan-containing ointment. The base of the fucoidan-containing microneedle is preferably a biosoluble polymer. This hair growth method is characterized by the combined use of a fucoidan-containing microneedle, and a fucoidan-containing ointment.