The present invention provides a method of analyzing methylated DNA, comprising steps of: (A) treating a DNA-containing sample with a restriction enzyme to obtain a sample containing a DNA fragment; (B) concentrating methylated DNA contained in the sample obtained in step (A) to obtain a methylated DNA concentrate; (C) subjecting the methylated DNA concentrate obtained in step (B) and a primer set to nucleic acid amplification reaction, wherein the primer set performs the nucleic acid amplification reaction in step (C) by using a template DNA which does not have a CpG site; (D) detecting an amplification product obtained in step (C); (E) judging whether the methylated DNA concentrate obtained in step (B) is appropriate as a sample for detection of methylated DNA, on the basis of the detection result of the amplification product in step (D); and (F) analyzing the methylated DNA contained in the methylated DNA concentrate.