This composition can be easily added when cryopreserving cells and improves cell viability. 1 volume % of the composition containing 0.01 wt % to 20 wt % of a sophorose lipid is added just before or up to 6 hours before cryopreservation and cells are stored. This composition can improve cryopreservation cell viability as it reduces freezing damage to cells. With this composition, cells can be stored without using DMSO and blood serum. This is a simple and inexpensive storage method as it does not require fine control of the freezing rate during cell cryopreservation.