A method of selecting a marker gene which is useful in identifying cancer; a method of identifying cancer by using this gene; a method of detecting cancer, a kit to be used in the identification or detection method; and a DNA array holding the above gene. Thus, it is possible to obtain a gene which shows a change in the expression dose independently from a gene showing a change in the expression specifically at the proliferation of cells and specifically to each cancer sample. Use of this gene makes it possible to conveniently and quickly identify or detect cancer withou resort to any surgical operations, thereby contributing to the diagnonis and treatment of cancer, etc.