Several fluvial terraces were developed in the Kajo Basin located in Kochang-gun, Kyongsangnam-do, Korea. The peat layers are formed on a fluvial terrace of them. To clarify the geomorphic development of this basin, a detailed classification of geomorphic surfaces, a soil profile study, grain size analysis, pollen analysis of the peat layers and C-14 dating were made. The main findings are as follows: 1) The Kajo Basin was formed by a differential erosion of granic rocks. The surrounding mountains are contact-metamorphosed gneiss and sedimentary rocks. 2) Seven geomorphic surfaces were recognized. They are named the H1, H2, M1, M2, T, L1 and L2 surfaces, from older to younger. 3) C-14 dating and the pollen analysis indicate that the L1 surface was formed during the Early Wurm Glacial. 4) The formation periods of the L2, M and H surfaces are supposed to be the Late Wurm, Riss and Mindel glacial, respectively, on the basis of the color of soil horizons (with or without the Red Soil) and the weathering degree of gravels. 5) Betula and Pices were dominant in the pollen of the Kajo Basin around 30,000 years B.P.