In the view point of phoniatrics, the understanding of the voice essence is very important. It is very important to establish the correct method of voice use by measurement of human voice limit and observation of changeable condition by acquired factors. The purpose of this study is, by understanding of voice essence, to provide the guidance of correct voice use and the prevention and the treatment of voice disorders of professional voice users. The results of comparative analysis between professional voice users as study group and non-professional voice users as control group are as follow ; 1) The voice limit of study group is 27-38 semitones and that of control group is 21-34 simitones. There is 4-6 semitones difference between study and control group. 2) According to the average voice limit of each grade, there is no significant difference in the study group but there is increasement of 2 seimitones per each grade in voice limit. 3) The persons who have longer voice training duration have much more high voice limit than who have shorter voice training duration. 4) Both control and study groups show that higher grades have higher voice limit. 5) The voice registers are higher in the study group than in the control group, but in the study group the voice register is obscure.