To provide a reflection mirror having a high reflectance in the visible region and excellent in moisture resistance and sulfur resistance, and its production process. A reflection mirror 10 comprising a substrate 11, a silicon nitride film 14 and a silver film 13 formed between the substrate 11 and the silicon nitride film 14, wherein when 10 ppm of hydrogen sulfide is introduced, and the reflection mirror is left to stand for 100 hours in an atmosphere at a temperature of 50° C. under a relative humidity of 80%, the rate of change of the luminous reflectance (chromaticity Y of the tristimulus value as defined in JIS Z8701 (1982)) after being left to stand is within 10% based on the luminous reflectance before being left to stand. Further, a process for producing a reflection mirror 10, which comprises forming a silver film 13 by a sputtering method and then forming a silicon nitride film 14 by a chemical vapor deposition method.