A bake system may include a chamber having an internal space, a stage disposed in the internal space of the chamber and on which a target substrate is disposed, a gas ejection structure providing a process gas in the chamber, an exhaust structure, an atmosphere analyzer monitoring moisture and oxygen in the chamber, and a gas supplier controlling a flow rate of the process gas based on information provided from the atmosphere analyzer. The exhaust structure may include a suction part disposed in the internal space, and an exhaust part connected to the suction part and is disposed outside the chamber.