PROBLEM TO BE SOLVED: To easily discriminate the sterile character of a plant by using a cytoplasmic male sterility factor DNA having a specific base sequence as a primer, amplifying a plant genom DNA by PCR method, separating by electrophoresis and visually detecting the objective DNA. SOLUTION: A genom DNA of a plant (e.g. carrot) is amplified by PCR method using an oligonucleotide effective for amplifying cytoplasmic male sterility factor DNA having a base sequence expressed by the formula, a part of the DNA, a DNA containing the DNA or a compound having the similar action as a primer. The amplified genom DNA is separated by electrophoresis and visually detected to enable the easy and quick confirmation of the genetic state of cytoplasmic male sterility character without necessitating much labor and long time. A plant having cytoplasmic male sterility factor DNA useful for the development of the breeding to control the fertility of a plant can be discriminated by this process.
