Abstract: To provide a method for selecting a marker gene useful for cancer classification; a method for classifying cancer using the gene; a method for detecting cancer; a kit usable for the classification method or detection method; and a DNA array carrying the gene. According to the present invention, there can be obtained a gene, wherein expression of the above gene is altered independently from genes each of which expression is altered specifically during cell proliferation and expression level of the above gene is specifically altered depending on every type of cancer samples to be tested, whereby the classification or detection of cancer can be carried out conveniently and quickly without giving surgical treatment. Therefore, the present invention is useful for the diagnosis, the treatment, and the like of cancer.