Method of extracting the contents from inside the reactor kept at high temperature and high pressure and the synthesis reaction system of a hydrocarbon compound

A method for extracting the contents from inside the reactor which is kept at high temperature and pressure, the contents of the reactor, a step of introducing into the pipe having an internal space which communicates with the reactor, closing the pipe a step of encapsulating the contents in the internal space, removing unnecessary gas from the internal space, the contents of the inert gas into the inner space enclosed in the internal space by supplying an inert gas and a step of substituting. By replacing the contents enclosed in the internal space with the inert gas, the contents from the interior space is discharged.