A DNA analysis method and a DNA analyzing device using terahertz wave capable of accurately determining a type of cancer from DNA using terahertz wave are disclosed. The DNA analysis method according to the present invention comprises: (a) irradiating terahertz wave onto methylated DNA; (b) detecting the terahertz wave reflected from the methylated DNA; (c) detecting a peak of a waveform of the terahertz wave detected in the step (b); and (d) determining type of cancer from the peak detected in the step (c).