A method for detaching a carrier for cell culture from cultured cells formed on a surface of said carrier, which includes the step of bringing the carrier for cell culture into contact with a compound represented by the following formula (I) or a polyphosphoric acid or a salt thereof: MO.sub.3P-L.sup.11-PO.sub.3M wherein L.sup.11 represents a divalent bridging group; and M represents a hydrogen atom or a cation. The carrier preferably includes a calcium alginate layer and a cell adhesion gel layer.