The present invention relates to a method for searching myelin using gonadotropin-releasing hormone receptors (GnRH-R) as a biomarker, more precisely, a method for investigating the distribution of myelin by immunohistochemical staining using GnRH-R antibody, based on the fact that GnRH-R and myelin are observed in the same region. The method for searching myelin of the invention can contribute to the studies on demyelination related degenerative brain disease and the disclosure of functions of myelin and the relation of myelin and GnRH-R.