A peripheral exposure method for performing an exposure treatment by illuminating light to a periphery of a resist film formed on a substrate to be processed is discussed. The method includes rotating the substrate to be processed on a horizontal plane, bringing a coolant gas into contact with the periphery of the resist film of the substrate to be processed which is being rotated, and cooling the substrate to be processed. Further, the method also includes measuring a temperature of the substrate to be processed, wherein when the temperature of the substrate to be processed is equal to or less than a predetermined temperature, the exposure treatment is performed.