It is an object of the present invention to provide a storing and/or transferring method of polyalkylene glycol monomers by which the gel-like matter formation and/or decomposition reaction can be satisfactorily inhibited and, as a result, troubles can be prevented from occurring in the production process and the performance characteristics or quality of various chemical products can be satisfactorily prevented from being deteriorated. A storing and/or transferring method of a polyalkylene glycol monomer which comprises storing and/or transferring a polyalkylene glycol monomer in the form of an aqueous solution.