To provide a gas nitriding method which can manufacture a plurality of nitrided components of which the required qualities are greatly different from each other, in the same furnace with the same treatment, and to provide a gas nitriding apparatus therefor.

The gas nitriding apparatus 1 includes: a gas nitriding furnace 2 which can accommodate a plurality of members 21 and 22 to be treated, while sequentially aligning the members; and a plurality of heating heaters 11 and 12 which are arranged in the gas nitriding furnace 2 so as to be aligned in the alignment direction of the plurality of the members 21 and 22 to be treated, and are constituted by materials having mutually different catalytic actions. The plurality of the members to be treated are accommodated in the gas nitriding furnace in a state of being sequentially aligned, and an ammonium gas G in the gas nitriding furnace is heated to a high temperature with the heating heaters 11 and 12. Thereby, the gas concentration of the ammonia gas G in the gas nitriding furnace 2 is varied in a direction in which the members 21 and 22 to be treated are aligned.

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