A cell cryopreservation method including adding a 1 volume % of a composition comprising 0.01 wt % to 20 wt % of a sophorose lipid to cells in a cell culture medium just before or up to 6 hours before cryopreserving the cells; and cryopreserving the cell culture medium, wherein the composition improves cell viability after cryopreservation compared to cells that are cryopreserved with a similar composition that does not contain the sophorose lipid.