PROBLEM TO BE SOLVED: To provide effective cancer treatment means through PSF1 gene expression inhibitory activity.SOLUTION: A PSF1 gene expression inhibitor comprises extracts of one or more plant selected from the group consisting of Cardiocrinum, Cardamine, and Pandanus polycephalus.【課題】PSF1遺伝子の発現抑制活性を通じた、より効果的ながんの治療手段を提供すること。【解決手段】ウバユリ、タネツケバナ、及びPandanus polycephalusから成る群より選択される1種以上の植物の抽出物を含む、PSF1遺伝子発現抑制剤。【選択図】図2