A new surface smoothing method using thermal nanoimprinting technology with a 0.2-nm-high atomically stepped sapphire mold has been investigated for quartz glass with a glass transition temperature (T g ) above 1000 °C. Atomic-scale patterning of approximately 0.1-nm-high step arrays has been achieved on the quartz glass. Imprinting was performed at 1.3 MPa and 1000 °C with loading for 10 min, and postannealing at 1000 °C for 180 min in vacuum was found to partially smooth the atomically stepped morphology of the glass surface.