Ten compounds have been isolated from the unused parts of Ammi visinaga. The isolated compounds were identified as tetracosanoic acid (1), β-sitosterol (2), visnadine (3), khellin (4), β-sitosterol glucoside (5), norkhellol (6), khellol (7), rhamnazin (8), cimifugin (9), and cis-khellactone-3’-β-glucopyranoside (10). The chemical structures of these compounds were elucidated based on spectroscopic data (NMR, UV, MS and IR spectra). This is the first report on the identification of tetracosanoic acid (1), norkhellol (6) and cimifugin (9) in the Ammi genus. The melanin biosynthesis inhibitory activities of khellin (4), khellol (7), visnadine (3), cimifugin (9), β-sitosterol (2) and β-sitosterol glucoside (5) were evaluated. Khellin (4) exhibited a potent melanin inhibitory effect compared to arbutin with less toxicity.