The performance and characteristics of a nanoparticle generator for in inhalation toxicity study of silver nanoparicle in SPF-SD rate were investigated. The nanoparticle generator is evaporation/condensation type using the ceramic plate heater. At the constant carrier gas(clean air) flow rate, the nanoparticle size distributions with various temperature conditions were measured by the SMPS system. The results showed that the geometric mean diameter and the total number concentration of nanoparticle increased with heater surface temperature. The particle generation was very stable since the temperature of heater surface was maintatined uniformly with time.