NZ在住の者です。過去10年間でドイツのヘンケルのナイフや日本の三徳包丁などを、昨年はDEAN & DELUCAの牛刀二丁を預け荷物で持ち込んだ経験があります。
入国審査では、申告さえすれば持ち込めます。

Even if the garden knife is brand new and straight out of the box, you must declare it on your New Zealand Traveller Declaration (NZTD) form.Why You Must Declare ItRisk category: Gardening tools are considered high-risk items by Biosecurity New Zealand because they are designed to contact soil and plants.The check-boxes: On your declaration form, you must tick "Yes" to the question asking about outdoor equipment or tools. If the knife has a wooden handle, you must also tick the box for wooden items.Inspection: Ticking "Yes" means a biosecurity officer will look at the knife at the airport. If it is brand new and clean, they will simply hand it back to you, and you can leave.Fines for forgetting: If you do not declare it and officers find it during a random bag scan, you can face an immediate $400 NZD fine for making a false declaration, even if the knife itself is perfectly clean.What to do at the NZ AirportFollow the red lane: Walk through the "Items to Declare" lane after collecting your luggage.Show the officer: Tell the biosecurity officer you have a brand-new garden knife from Japan.Keep packaging: It is easiest if you leave the knife inside its original Japanese retail packaging so the officer can clearly see it has never been used in soil.