A method of processing an object using a plasma processing apparatus is provided. The plasma processing apparatus includes a stage on which the object is placed in a chamber, an outer peripheral member disposed around the stage, a first power supply configured to apply voltage to the outer peripheral member, and a memory storing information about a relationship between the voltage applied to the outer peripheral member and an adjustment amount of a process parameter. The method includes: applying voltage from the first power supply to the outer peripheral member; adjusting the process parameter based on the voltage applied to the outer peripheral member, by referring to the information stored in the memory; and performing a plasma process under a process condition including the adjusted process parameter.