A generation method of in-situ gold nanoparticles using a small-sized ceramic heater with a local heating area is presented. The heater surface temperature was maintained uniformly. Gold nanoparticles with high concentration (> 107 particles/cm3) were produced and were stably generated for several hours because the heater surface temperature was maintained uniformly. Higher surface temperature yielded higher geometric mean diameter (GMD), geometric standard deviation (GSD), and total number concentration. Using this generator particle size distribution was easily controlled. Spherical and non-agglomerated nanoparticles were observed from TEM images, even at high concentration and high temperature. Although air was used as a carrier gas, the generated gold nanoparticles displayed pure crystallinity of the gold element, as determined by XRD analysis.