A process for preparing a high purity (meth)acryloyloxyalkyl isocyanate having a very small hydrolyzable chlorine content is provided. The high purity (meth)acryloyloxyalkyl isocyanate is prepared by subjecting a hydrolyzable chlorine containing (meth)acryloyloxyalkyl isocyanate to mixing treatment with an epoxy compound and an amine at a temperature of from 110 to 160.degree. C. to prepare a mixture; and preparing a high purity (meth)acryloyloxyalkyl isocyanate from the resulting mixture with distillation. In particular, it is possible to effectively prevent (meth)acryloyloxyalkyl isocyanate from polymerization during the distillation by adding a polymerization inhibitor such as phenothiazine and the like.