Provided are: a cell population which is essentially formed from mammalian cells in which cell surface markers CD31 and CD200 are positive, and cell surface marker CD45 is negative; a cell population which is essentially formed from mammalian cells in which cell surface markers CD31, CD157, and CD200 are positive, and cell surface marker CD45 is negative; mammalian vascular endothelial stem cells in which cell surface marker CD31 is positive, cell surface marker CD157 and/or cell surface marker CD200 are/is positive, and cell surface marker CD45 is negative; and a revascularizing pharmaceutical having, as an active ingredient, the cell populations or the vascular endothelial stem cells.