In one embodiment, a steam device includes a high-temperature member and a low-temperature member. One surface of the high-temperature member is exposed to high-temperature steam, and the other surface is cooled by cooling steam having a temperature lower than the high-temperature steam. The low-temperature member is disposed to face the high-temperature member with a passage for the cooling steam therebetween and is formed of a material having a heat resistance lower than that of the high-temperature member. The steam device has at least one high-reflectance film selected from a first high-reflectance film, which is formed on the surface of the high-temperature member which is exposed to the high-temperature steam and has a higher reflectance with respect to infrared rays than the high-temperature member, and a second high-reflectance film, which is formed on the surface of the low-temperature member facing the high-temperature member and has a higher reflectance with respect to infrared rays than the low-temperature member.