Volcanic ash becomes environmental important issues as waste material if it is not effectively reduced or reused. In engineering practice, utilization of volcanic ash as substitution material is limited. Indonesia has a large road on soft soil and volcanic ash. The objectives of this paper are focused to study the characterization, classification and utilization of volcanic ash as soil stabilization material which give benefit in engineering practice and also be environmental friendly material. Engineering properties, mineral composition and soil mixture characteristics involve physical and mechanical properties are discussed. Result shows that the effect of addition of volcanic ash after curing time 14 days can improve the engineering properties of soft soil, decrease liquid limit, change curve of grain size distribution, increase bearing capacity, and decrease swelling potential. The soil-volcanic ash mixture with 35% of volcanic ash and 5% of lime is obtained as optimum mixture design. This result is still early stage and need further study.