Despite the complexity and variability, the entity of sounds in particular time and space characterises the environment. Japanese people have an idea that the riverside environment provides important sound resources for comfort and relaxation, and attempt to include it in the local area planning. However, what is the riverain sound environment in bioacoustic senses? The Tone River, which covers a large area of mountains and plains in north and east of Tokyo, has historically been altered in many ways such as flood control and other human activities. In 1993-94, the sound environment survey was carried out from the lower reach of artificially constructed river banks, along the middle reach amidst the plain of agricultural activities to the upper reach of natural mountain forest tributaries. The present paper focuses upon the analysis methods to characterise the varieties of sound environment along the river. From identification of natural sound sources and examination of recorded samples using wave form, power spectrum and sonogram methods, I attempted to relate the sound source composition and their acoustic features to the land utilisation and structure of environment. It appears that the present method may provide a useful method to understand the structure of sound environment.