The present invention relates to a novel strain Pseudoalteromonas sp. The exopolysaccharide derived from the CY01 strain (KCTC 12867BP) and a composition for cryoprotection of cells containing the same, the exopolysaccharide of the present invention has an excellent cell cryoprotective ability during cryopreservation and is cytotoxic. Can be substituted for existing cryoprotective agents that have been cytotoxic at high concentrations.本発明は、極地方に生息する新規菌株のPseudoalteromonas sp. CY01株(KCTC 12867BP)由来の菌体外多糖及びこれを含有する細胞の凍結保護用組成物に関し、本発明の菌体外多糖は、凍結保存時に優れた細胞凍結保護能を有し、細胞毒性を示さず、既存の高濃度で細胞毒性を示した凍結保護剤に代替することができる。