A process for producing a reflective mask blank for EUV lithography (EUVL), which comprises forming a multilayer reflective film for reflecting EUV light on a film-forming surface of a substrate, then forming a protective layer for protecting the multilayer reflective film, on the multilayer reflective film, and forming an absorber layer for absorbing EUV light, on the protective layer, to produce a reflective mask blank for EUVL, wherein the multilayer reflective film is a Mo/Si multilayer reflective film, the protective layer is a Ru layer or a Ru compound layer, the absorber layer is a layer containing at least Ta and N, and after forming the Mo/Si multilayer reflective film, the protective layer is formed, and after forming a Si thin film or Si oxide thin film having a thickness of at most 2 nm on the protective layer, the absorber layer is formed.