The paper reports a highly sensitive SnO2-based gas sensor fabricated with radio-frequency induction plasma deposition (IPD) method. The generated sensing film consisted of various nano-sized particles, and they were found to be very sensitive to indoor air pollutants such as formaldehyde (HCHO) and nitrogen dioxide (NO2) gas at extremely low gas concentration down to 20 ppb (parts-per-billion) with rapid response and recovery time less than several minutes. The physical properties of the sensing films were examined by SEM and XRD methods. The effects of posterior annealing treatment and temperature dependency on the sensors were also described in the paper. The results suggested that the fabricated sensors are promising for monitoring indoor air pollution.