To provide a reflective mask blank for EUV lithography having an absorber layer, which presents a low reflectance to a light in the wavelength ranges of EUV light and pattern inspection light, and which is easily controlled to have desired film composition and film thickness. A reflective mask blank for EUV lithography, comprising a substrate, and a reflective layer for reflecting EUV light and an absorber layer for absorbing EUV light formed in this order on the substrate, wherein the absorber layer contains tantalum (Ta), boron (B), silicon (Si) and nitrogen (N), and in the absorber layer, the B content is at least 1 at % and less than 5 at %, the Si content is from 1 to 25 at %, and the compositional ratio of Ta to N (Ta:N) is from 8:1 to 1:1.