A method for detecting DNA methylation and modifications is developed using biological nanopores. By exploiting the interaction between bases and acidic amino acids within the entrance and neck region of the α-hemolysin nanopore, we determined the position and frequency of 5-methylcytosine in oligonucleotides. Furthermore, the detection of demethylation intermediates is optimized by examining various ion species and concentrations in the electrolyte. Efforts are also made to employ commercial nanopore devices for high-throughput detection. This approach offers the potential for direct detection of DNA methylation and modifications using biological nanopores.