Hokosshi extract is obtained by ethanol extraction from the seeds of hokosshi (Psoralea corylifolia), which is used as a Chinese medicine. The constituents of hokosshi extract were analyzed. The main constituent was isolated using column chromatography, and identified as bakuchiol by TLC, LC/MS and NMR. Bavachinin A was also detected. In order to prepare a marker substance for hokosshi extract, bakuchiol was isolated from seeds of hokosshi using Sep-Pak cartridges. An analytical method for hokosshi extract in foods based on detection of bakuchiol was developed. Bakuchiol was extracted from food with 60 vol% ethanol. The extract was cleaned up using a Sep-Pak plus C18 cartridge, and bakuchiol was determined by HPLC. Seasoning and juice were spiked with hokosshi extract at 500 micrograms/g and analyzed by the proposed method. The recoveries of bakuchiol were 72-99%. The detection limit for the assay was 25 micrograms/g.