A heating method includes an oxide film forming step and a heating step. The thickness of an oxide film is set in a first range that includes a first maximal thickness and a second maximal thickness and that is smaller than a second minimal thickness in the relationship with the laser absorption having a periodic profile. The first maximal thickness corresponds to a first maximal value a of the laser absorption. The second maximal thickness corresponds to a second maximal value of the laser absorption. The second minimal thickness corresponds to a second minimal value of the laser absorption, namely the minimal value of the laser absorption that appears between the second maximal value and a third maximal value, or the maximal value of the laser absorption that appears subsequent to the second maximal value.