1. The plant communities on Mt. Sulak, a typical alpine mountain in central Korea was researched from the standpoint of ecological survey. 2. The plant on this mountain can largely be classified into 2 categories, the warm zone (below 1100m) and the frigid zone. The former is again classified into a broad-leaved tree formation and a needle-leved tree formation, and the latter is calssified into a broad-leaved tree formation and needle-leaved tree formation, and shrub formation. 3. The broad-leaved tree formation in the warm zone can largely be classified into a Carpinus laxiflora-syringa Palibiniana var. kanibayashi association(1), a Carpinus erosa-Acer Pseudo-sieboldianun association(2), and a Quercus mongolica- Tripterygium Regelii association(3). 4. The needle-leaved tree formation in the warm zone can also largely ben classified into a Pinus densiflora- Miscanthus sinensis association(4), Abies holophylla- Tripterygium regelii association(5), Pinus kordiensis- Rhododendron schlippenbachii association(6) In the association(4), the canopy of the Pinus densiflora is gradually being occupied by the Quercus mongolica which is one kind of broad-leaved trees. 5. We can fully see a DryoPteris type of the flour layer plant type in the association (3) and also see a Sasamorpha type in the association (5). 6. The broad-leaved tree formation in the frigid zone can largely be classified into Quercus mongolica- Rhododendron schlippenbachii association (8). The constituents of tree and subtree layers in (7) and (8) associations are similar to those association (3), but the constituents of the shrub layer are different from those of associtation (3) due to the difference in height. 7. The needle-leaved formation in the frigid zone can largely be classified into Thuja koraiensisRodgersia podophylla var. viritis association (9) and Abies nephrolepis-Acer tschonoskii var. rubripes asscciation (10). The species of alpine plants or subalpine plants are gradually increased in this formation. 8. The shrub formation can also largely be classified into a Rhododendron mucronulatum- Patrinia saniculaefolia association (11) and Pinus pumila associatio (12). Association (12) has largely developed on the windy place. Association (12) was burned due to the bombing during the Korean war, but now we recoginized there occurred an invasion of Tripterygium Regelii in such a place. 9. The herb layer species which constitute the shrub formation are mostly alpine or subalpine plants of small size, and their kinds are also very few. 10. The growth of the Moss layer is especially good because of the varied conditions of the habitat. The kinds which can easily be seen are the genus of Thunidium, Haplocladium, Brachythecium, Macromitrium, Holonitrium, Atrichum, Schwstchkeopsis, Grimmia, Hedwigia, Rhynchostegium and Mnium. 11. The genus of the Sphagnum densly grows like a mat at the acid and moisturous place above 1100m. The authors should express their thanks to father. Yang Kisup, Dean of Catholic Medical College, Prof. Yoon Doksuen, from their valuable advice. Thanks arealso due to Prof. Numata, Chiba University, Prof. Takagi, Nagoya University and Prof. Ando, Hiroshima University in Japan for his kind help and identification of Bryophytes.