PROBLEM TO BE SOLVED: To give a repeatability to the temperature of floating kit parts between treatment of wafers. SOLUTION: In a plasma treatment chamber, warm-up plasma is formed in the interior of the chamber to heat floating kit parts in the time when a prescribed plasma treatment procedure (recipe) is not executed in the chamber. The temperature of the floating kit parts are maintained in the range of the respective schedule target temperatures of the floating kit parts during the time when a scheduled plasma treatment is not performed using warm-up plasma other than that in this recipe.