Oligonucleotide-immobilized substrate for detecting methylation

Presence or absence of methylation of C located on 5′ side of G in a sample DNA comprising a target sequence containing a dinucleotide consisting of C that may be methylated and a nucleotide on the 3′ side of the C (CpN dinucleotide) is determined based on a result of hybridization performed for a plurality of capture oligonucleotides immobilized on a base material and including at least an oligonucleotide having a nucleotide sequence complimentary to or identical to a nucleotide sequence corresponding to the target sequence in which C other than C in the CpN dinucleotide is replaced with T and an oligonucleotide having a nucleotide sequence complimentary to or identical to a nucleotide sequence corresponding to the target sequence in which all of C's are replaced with T's and the sample DNA in which cytosines not methylated are converted into uracils by deamination or an amplification product thereof.