飛行機にBackpack / Extra Bagを持ち込める？
Yes — you can bring backpack on a plane in your carry-on luggage. Security: unlimited bag types.
- · Security: unlimited bag types
- · Two backpacks on a plane = your allowance: 1 cabin bag + 1 under-seat personal item on most full-service airlines
- · Basic Economy (United) / ULCC fares: often personal item only — the second bag costs extra
- · Sizing: under-seat ≈ 18 × 14 × 8 in; overhead ≈ 22 × 14 × 9 in on most US airlines
On this page · 6 sections
航空保安当局別の公式規定
Rules by security authority
United States — TSA
Carry-on
Yes
Yes, a backpack is allowed — security has no bag-type rules. The airline decides whether it is your carry-on (overhead) or personal item (under seat).
Checked bag
Yes
Yes, backpacks can be checked — cinch all straps or use a cover so they do not snag the conveyor.
Flying internationally? Security follows the country you depart from — the authority above applies at your departure airport. Customs at arrival is separate.
航空会社別の追加ルール
The two-backpack question is really a fare question: full-service economy includes cabin bag + personal item; United Basic (domestic) and every ULCC base fare include only the under-seat item. Compare all airlines below.
Backpack / Extra Bagのパッキング注意点
機内持ち込み手荷物: Yes, a backpack is allowed — security has no bag-type rules. The airline decides whether it is your carry-on (overhead) or personal item (under seat).
受託手荷物（預け荷物）: Yes, backpacks can be checked — cinch all straps or use a cover so they do not snag the conveyor.
保安検査場での最終的な持ち込み可否判断は、現場の保安検査員に委ねられます。
よくある質問 (FAQ)
Frequently asked questions
Can you bring a Backpack in a carry-on?
Yes, a backpack is allowed — security has no bag-type rules. The airline decides whether it is your carry-on (overhead) or personal item (under seat).
Can you pack a Backpack in checked luggage?
Yes, backpacks can be checked — cinch all straps or use a cover so they do not snag the conveyor.
Can I carry two backpacks on a plane?
Yes on most full-service airlines: one fits the overhead as your carry-on, the other fits under the seat as your personal item. On United Basic Economy and ultra-low-cost carriers, only the under-seat one is free.
What size duffel bag can I carry on a plane?
The same as a suitcase: about 22 × 14 × 9 in (56 × 36 × 23 cm) including external pockets on most US airlines. Duffels compress, so slightly oversized soft bags usually pass.
Do airlines have their own rules for a backpack?
The two-backpack question is really a fare question: full-service economy includes cabin bag + personal item; United Basic (domestic) and every ULCC base fare include only the under-seat item. Compare all airlines below.
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