Cowpea (Vigna sinensis K.) seeds were extracted with 80% aqueous methanol. Concentrated extracts were partitioned with ethyl acetate, butanol, and $H_2O$, successively. The repeated silica gel and octadecyl silica gel (ODS) column chromatographic separations for the butanol fraction led to isolation of four sterols, whose chemical structures were determined as $7{eta}$-hydroxysitosterol (1), $7{alpha}$-hydroxysitosterol (2), 7-ketositosterol (3), and stigmasterol 3-O-${eta}$-D-glucopyranoside (4) from the interpretation of spectroscopic data including NMR, mass spectroscopy, and infrared spectroscopy (IR). This paper reports the first isolation of compounds 1 and 2 from V. sinensis seeds. All compounds were evaluated for the effect on heme oxygenase-1 (HO-1) expression, which is considered to be an antioxidant enzyme that catabolizes heme into carbon monoxide, free iron, and biliverdin. All sterols increased the expression of HO-1 in HepG2 cells.