The present invention relates to a hair growth stimulator based on an Ecklonia cava extract, a preparation method thereof and a cosmetic composition containing the same. Dioxinodehydroeckol is isolated from the Ecklonia cava extract. The Ecklonia cava extract prepared according to the preparation method and the dioxinodehydroeckol compound have excellent hair growth effects which are significantly higher than the effect of an Ecklonia cava extract prepared according to a conventional method.
