An object of the present invention is to provide a method for stabilizing an acrylic acid derivative, and a composition containing an acrylic acid derivative in which the acrylic acid derivative is stabilized. The present invention provides a composition comprising: (A) an acrylic acid derivative represented by Formula (I): (wherein Ra represents alkyl, fluoroalkyl, aryl that may have one or more substituents, or hydrogen; and X represents fluorine, alkyl, perfluoroalkyl, or hydrogen); and (B) aldehyde, wherein the content of acrylic acid derivative (A) is 30% (w/w) or more.