A processing system of the present invention includes: a reaction container in which a substrate to be processed is placed, a process-gas supplying mechanism that supplies a process gas into the reaction container at a process to the substrate, a cleaning-gas supplying mechanism that supplies a corrosive cleaning gas into the reaction container at a cleaning process, a gas-discharging-way member connected to the reaction chamber, a heating unit that heats a specific portion of the reaction container and the gas-discharging-way member, a temperature detecting unit that detects a temperature of the specific portion, a temperature controlling unit that controls the heating unit based on a detection value detected by the temperature detecting unit in such a manner that the specific portion becomes to a predetermined target temperature, and a temperature changing unit that changes the target temperature between at the process to the substrate and at the cleaning process. By means of the temperature changing unit, the target temperature is set to a temperature at which adhesion of reaction by-products to the specific portion may be inhibited, at the process to the substrate, while the target temperature is set to a temperature at which corrosion of the specific portion may be inhibited, at the cleaning process.