Quinone reductase (QR) is a protective phase II enzyme against mutagens and carcinogens which is inducible by a number of chemical compounds in plants. This study was carried out to investigate effects of the fractions from the seeds of Psoralea corylifolia on the induction of QR with Hepa 1c1c7 murine hepatoma cell line. The ethyl acetate-soluble fraction of the methanolic extract from the seeds was found to induce QR and the concentration of 1.5 fold QR induction (1.5 FIC) was $1.2;{mu}g/mL$. We obtained as an active compound, psoralidin, isolated from the ethyl acetate-soluble fraction after further sequential fractionation with column chromatography and 1.5 FIC of psoralidin was $0.5;{mu}g/mL$. The seeds of Psoralea corylifolia and psoralidin might be a candidate for developing QR inducers.