On the basis of the recently available data, we have analysed the kinematical properties of nearby dwarfs, which are grouped by their spectral types and derived their ages from the kinematical properties. The discontinuities in the kinematical properties are found around late F stars, which appear to be caused mainly by the fact that the spectral groups earlier than late F are rather homogencous in age while the later ones are mixed by two different age group.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. KINEMATICAL PROPERTIES OF SPECTRAL GROUPS AND THEIR AGES
Ⅲ. CONCLUDING REMARK
REFERENCES

• S. G. LEE(Department of Astronomy, Seoul National University)