The influence of the music sound to our hearing and the conception of the music as a noise hazard or a source of acoustic trauma have been discussed since 1960's by many authors. Moreover the trend of the headphone use for enjoying music seems to be increased recently. To investigate the actual states of the headphone-use in teenagers of our country, the authors distributed a questionnaire to 1701 students of the two boys and girls senior high school. And also studied the M.C.L.(Most Comfortable Level) degrees during use of the headphone to the 227 girls of the same senior high school as above mentioned. At the same time, the authors performed audiometric screening test to 221 girl students, who were suspected never having such factors or past history to influence their hearing abilty. The results were as follows : 1) The rate of headphone user was 29.0% (495 students) among 1701 students. The cases who had career of the headphone-use below 1 year were 54.7% of the headphone-users, and 48.5% of the headphone-user applied headphone 1 to 2 times per week. The cases who had the average duration of the headphone-use below 1 hour in each time were 78.7% of the headphone-user, and 71.5% of the headphoneuser answered their subjective feelings of the sound volume during headphoneuse to be adequate. 50.3% of the headphone user replied that their main liking music was pop-song(foreign) and 29.1% of the headphone-user complained subjective symptoms such as fulness of ear, tinnitus and mild headache immediately after headphone-use. Mini-headphone users were 30.1% of the total headphone-user. 2) In study for M.C.L. degree during headphone-use, the mean M.C.L. of the total subjects (227) was 83.7 dB. While the mean M.C.L. of the headphone-user (94) was 86.1 dB, the headphone non-user (133) showed the mean M.C.L. of 81.9 dB. The cases who had the M.C.L. over 95 dB during use of the headphone were 20, and 15 cases of them were headphone-user and the other 5 cases were headphone non-user. 3) The results of audiometric screening test of 221 students who were suspected never having such factors or past histories to influence their hearing ability revealed 18 cases (18.1%) having the abnormal hearing ability, and 10 cases of them were headphone-user and 8 cases were headphone non-user. All of them showed the audiotory threshold below the 30 dB in two frequency (1k Hz, 4k Hz).