A spraying and re-heating vapor reactor includes: a heat preservation boiler; a vapor reaction boiler disposed in the heat preservation boiler; a re-heating conduit communicating the vapor reaction boiler with a device outside the heat preservation boiler, a high heat capacity material being accommodated within the heat preservation boiler, and surrounding the vapor reaction boiler and the re-heating conduit; a heater heating the high heat capacity material; a sprayer disposed in the vapor reaction boiler; and a liquid supplying tube communicating with the sprayer through structure walls of the heat preservation boiler and the vapor reaction boiler, and supplying an external liquid to the sprayer. The sprayer atomizes the external liquid into an atomized liquid absorbing thermal energy from the high heat capacity material and becomes a low-temperature vapor entering the re-heating conduit and being re-heated into a high-temperature vapor. A generator apparatus is also provided.