There are provided an EUV optical member, in which deterioration in the reflectivity due to oxidation of the Ru protective layer is prevented, a functional film-equipped substrate to be employed for production of the EUV optical member. A reflective layer-equipped substrate for EUV lithography comprising a substrate, and a reflective layer for reflecting EUV light and a protective layer for protecting the reflective layer, formed in this order on the substrate, wherein the reflective layer is a Mo/Si multilayer reflective film, the protective layer has a three-layer structure wherein a first layer made of a Ru layer or a Ru compound layer, a second layer made of a Mo layer and a third layer made of a Ru layer or a Ru compound layer are laminated in this order on the reflective layer.