Provided is a pyrolysis furnace having a gas flowing path controller with an improved structure. The pyrolysis furnace includes: a silicon substrate; a main body of the pyrolysis furnace; a heating unit that is formed around the main body and controls the temperature of the main body; at least one gas supplying tube through which a gas flows into the main body; and a gas flowing path controller that is installed inside the main body and controls the flow of the gas. As a result, controlling and manufacturing of small-sized nanoparticles with excellent characteristics is possible.