Litrature survey was carried out on the thickness design methods for bituminous airport pavement. Studies were the welknown methods published from seven organizations, that is, U.S. Corps of Engineers (C.B.R. Method), U.S.Navy, U.S.Federal Aviation Agency, Asphalt Institute of U.S.A., English Ministry of Public Building and Works (L.C.N. Method (,Canadian Ministry of Transport (McLeod Method)and French Ministry of Transportation. Among these methods the C.B.R. Method seems most reliable since it has been developed based on sufficient field experiences and full scale proof tests far more than any other method. It is rather strange, however, that the total pavement thickness obtained by the method is constant irrespective of the C.B.R. values of pavement materials as far as the C.B.R. value of subgrade is maintained uncharged. It is considered more rational to modify the tatal pavement thickness based on the C.B.R. Method by introducing the concept of layer equivalency of pavement materials.