This study was conducted to evaluate the effect of Acanthopanax koreanum and acankoreoside J from A. koreanum on the promotion of hair growth. When immortalized rat vibrissa dermal papilla cells were treated with extract of A. koreanum leaves, the proliferation of dermal papilla cells significantly increased. In particular, acankoreoside J among several components, isolated from A. koreanum leaves, markedly promoted the proliferation of the dermal papilla cells. When rat vibrissa follicles were treated with an acankoreoside J, the hair-fiber lengths of the vibrissa follicles increased significantly. We further investigated ${eta}$-catenin pathway and cell cycle regulation with respect to the effect of acankoreoside J on the proliferation of the dermal papilla cells. Treatment with acankoreoside J results in an increase of nuclear ${eta}$-catenin level, and up-regulation of cyclin D1, cyclin E and CDK2, whereas, the expression of $p27^{kip1}$ was down-regulated in the dermal papilla cells. Taken together, these results suggest that acankoreoside J, a lupane-triterpene of A. koreanum, has the potential of promoting hair growth by promoting cell cycle progression of the dermal papilla cells, through the increase of nuclear ${eta}$-catenin, along with the up-regulation of cyclin D1, cyclin E and CDK2, and down-regulation of $p27^{kip1}$.