It is an object to obtain from a mixture of a specific diene compound (1) and a compound (2) with the same molecular weight and molecular formula hard to separate by distillation, the diene compound (1) in high purity without using any special reagent or complicated technique.Namely, the present invention provides a method of inducing the Claisen rearrangement reaction of the compound (2) in a mixture containing CR.sup.1R.sup.2.dbd.CR.sup.3CFR.sup.4CR.sup.5R.sup.6OCR.sup.7.dbd.CR.sup.- 8R.sup.9 (1) and CFR.sup.1R.sup.2CR.sup.3.dbd.CR.sup.4CR.sup.5R.sup.6OCR.sup.7.dbd.CR.sup.- 8R.sup.9 (2), and separating the diene compound (1) from a Claisen rearrangement reaction product; or converting the Claisen rearrangement reaction product into a derivative and then separating the diene compound (1) from the derivative of the Claisen rearrangement reaction product. Wherein, R.sup.1 to R.sup.9 each represent a fluorine atom or the like.