Polyurea microcapsules were prepared by interfacial polymerization between water-soluble diamine monomer and oil-soluble diisocyanate monomer. Fragrant oil was incorporated in diisocyanate for the core material. The O/W type emulsions were prepared under various conditions of emulsification. FT-IR, thermal analysis, particle size analysis, SEM observation, and HPLC methods were used in investigating the characteristics of microcapsules. The mocrocapsules were spherical and the mean diameters were in the range of 5${mu}{ extrm}{m}$ to 10${mu}{ extrm}{m}$. The particle size and amount of core material could be controlled by governing the conditions of the emulsification process. The HPLC results showed that the estimated degree of microencapsulation was above 80%, and that the release of core materials could be controlled by varying the heat treatment conditions.