7-Phloroeckol, phloroglucinol derivative isolated from marine brown algae, has anti-oxidative, anti-inflammatory responses and MMP inhibitory activities. In this study, we evaluated the hair growth-promoting effects of 7-phloroeckol in human hair follicles. To investigate cell viability of human dermal papilla cells (DPCs) and outer root sheath (ORS) cells in the presence or absence of 7-phloroeckol treatment, MTT assay was employed. Moreover, gene expression and protein concentration of insulin-like growth factor (IGF)-1 was measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. 7-Phloroeckol induced an increase in proliferation of DPCs and ORS cells. In addition, hair shaft growth was measured using the hair-follicle organ culture system. 7-Phloroeckol resulted in elongation of the hair shaft in cultured human hair follicles. 7-Phloroeckol induced an IGF-1 mRNA expression and protein concentration in DPCs and conditioned media, respectively. These results suggest that 7-phloroeckol promotes hair growth through stimulation of DPCs and ORS cells.