Provided is a reflective mask blank with which it is possible to further reduce the shadowing effect of a reflective mask, and also possible to form a fine and highly accurate phase-shift pattern. A reflective mask blank having, in the following order on a substrate, a multilayer reflective film and a phase-shift film that shifts the phase of EUV light, said reflective mask blank characterized in that: the phase-shift film has a first layer and a second layer; the first layer comprises a material that contains at least one element from among tantalum (Ta) and chromium (Cr); and the second layer comprises a metal-containing material that contains ruthenium (Ru) and at least one element from among chromium (Cr), nickel (Ni), cobalt (Co), vanadium (V), niobium (Nb), molybdenum (Mo), tungsten (W), and rhenium (Re).