The Cardinal principle of ear operation is control of infection through eradication of disease and reconstruction of the middle ear sound conducting mechanism. Hearing improvement after tympanoplasty was affected by Eustachian tube function and middle ear space. In Korea, still there is no report about acoustic impedance studies in tympanoplasty, so we measured the acoustic impedance in 113 cases who had hearing improvement after tympanoplasty and analized them. The results are as follows : 1) Tympanogram A type was most prevalent in tympanoplasty Type I with 34 cases(70.8%), and in Type II with 12 cases(60%) and in Type III with 15 cases (42.8%) were following. 2) In tympanogram A type, Type I showed that postop A-B gap within 20dB is 27 cases(56.3%) but there was no relation between tympanogram type and hearing improvement in Type II and Type III. 3) Static compliance was 0.28±0.18 cc in Type I, 0.23±0.19 in Type II, 0.21±0.16 in Type III. 4) In graft position, static compliance was 0.23±0.19 cc in onlay technique, and 0.22±0.18 cc in underlay technique.