An object of the present invention is to provide a substrate with a multilayer reflective film, which gives a reflective mask achieving high reflectance and exhibiting excellent cleaning resistance. The present invention is directed to a substrate with a multilayer reflective film, which has: a substrate; a multilayer reflective film, formed on the substrate, comprising a layer that includes Si as a high refractive-index material and a layer that include a low refractive-index material, the layers being periodically laminated; a Ru protective film, formed on the multilayer reflective film, for protecting the multilayer reflective film; and a block layer, formed between the multilayer reflective film and the Ru protective film, for preventing the migration of Si to the Ru protective film, wherein the surface layer of the multilayer reflective film opposite from the substrate is the layer comprising Si, and at least part of the Si is diffused into the block layer.