A processing apparatus includes a first detection unit for detecting a temperature of an inner wall of the vacuum vessel, a second detection unit for detecting a temperature of the processing unit, and a first control unit for controlling a temperature of the gas. The first control unit controls the temperature of the gas based on a temperature gradient between the temperatures of the inner wall and the gas or a temperature gradient between the temperatures of the processing unit and the gas. A method for removing particles from a processing apparatus includes a first detection step for detecting a temperature of an inner wall of the vacuum vessel, a second detection step for detecting a temperature of the processing unit, a first control step for controlling a temperature of the gas, and a gas introduction step for introducing the gas into the inner space of the vacuum vessel.