Background and Objectives : A post-pubescent male classical singer has lower vocal register than a female classical singer. Countertenors who can produce higher vocal register like female classical singers with their falsetto voice and head resonance are recently active. The general purpose of this study is to analyze voice of countertenors and to determine the differences with those of classical singers. Materials and Methods : Four countertenors in Korea were examined using a videostrobos-copy and their voice were analyzed using aerodynamic, acoustic and voice range profile methods. Results and Conclusion : Countertenors could produce elevated fundamental frequency, voice intensity and mean air flow rate using large pulmonary capacity and head voiced falsetto. It means the presence of greater energy in countertenor is due to the more efficient conversion of the air flow to acoustic energy. But, they had unstable amplitude perturbation per each vocal cycle. The results indicated that countertenor is the acoustic products of different laryngeal mechanism with other classical register and it can be recognized as one of the registers of male classical singers.