To provide a hair growth tonic exhibiting an excellent hair growth effect.

This hair growth tonic containing the aqueous solution of a water-soluble dimer iron salt (ferrous ferric chloride)is characterized in that the aqueous solution contains magnesium ion and calcium ion. The hair growth tonic is characterized by further containing the extracts of Lycium chinense and Acanthopanax senticosus. The hair growth tonic has a hair growth effect for promoting the proliferation and differentiation of keratinocyte, melanoblast and melanocyte which participate in the growth of hair. The aqueous solution of the water-soluble dimer iron salt is also used for drinking water, and therefore does not give an undesirable irritation to scalps.