国道339号（こくどう339ごう）は、青森県弘前市から東津軽郡外ヶ浜町（三厩地区）に至る一般国道である。

概要

青森県弘前市から津軽平野を北上して五所川原市を経由し、津軽半島北端の東津軽郡外ヶ浜町（三厩地区）に至る延長129.3 kmの一般国道の路線で、主な通過地は、南津軽郡藤崎町、北津軽郡板柳町、同郡鶴田町、五所川原市、北津軽郡中泊町大字中里、同町大字小泊である。津軽半島の中央部を南北に縦断する道路で、半島北部は日本海側に道路が沿っており、竜飛崎と小泊を結ぶ区間は通称「竜泊ライン（たつどまりライン）」とよばれる。東津軽郡外ヶ浜町龍浜の竜飛崎附近に、国道で唯一の階段と歩道で構成された車両通行不能区間があり、「階段国道」の名で特に知られる。

路線データ

一般国道の路線を指定する政令に基づく起終点および重要な経過地は次のとおり。

起点：弘前市（運動公園入口交差点 = 国道7号上、国道102号・青森県道109号弘前平賀線起点）

終点：青森県東津軽郡三厩村（国道280号交点、青森県道230号三厩停車場線終点）

重要な経過地：青森県南津軽郡藤崎町、五所川原市、同県北津軽郡中里町

総延長 : 129.3 km（重用延長を含む。）

重用延長 : 0.0 km

未供用延長 : なし

実延長 : 129.3 km

現道 : 96.4 km

旧道 : 0.6 km

新道 : 32.3 km

指定区間：国道7号と重複する区間（弘前市・運動公園入口交差点（起点） - 南津軽郡藤崎町・舟場交差点 / 国道339号バイパス入口交差点）

National Route 339 is a general national highway running from Hirosaki City to the town of Sotogahama (Minmaya district) in Higashitsugaru District, Aomori Prefecture. Overview With a total length of 129.3 km, this general national highway runs northward through the Tsugaru Plain from Hirosaki, Aomori Prefecture, passing through Goshogawara to reach Sotogahama (Minmaya district) in Higashitsugaru District at the northern tip of the Tsugaru Peninsula. Its major transit points include Fujisaki in Minamitsugaru District, Itayanagi and Tsuruta in Kitatsugaru District, Goshogawara, and the Nakasato and Kodomari areas of Nakadomari in Kitatsugaru District. The road traverses the center of the Tsugaru Peninsula from south to north, running along the Sea of Japan coast in the northern part of the peninsula; the section connecting Cape Tappi and Kodomari is commonly known as the "Tatsudomari Line." Near Cape Tappi in the Tappizaki area of Sotogahama, Higashitsugaru District, there is an impassable section for vehicles consisting entirely of stairs and a pedestrian path—the only such section on a Japanese national highway—and it is widely known as the "Staircase Highway" (Kaidan Kokudo). Route Data The origin, terminus, and major transit points based on the Cabinet Order designating general national highway routes are as follows: Origin: Hirosaki City (Sports Park Entrance Intersection = on National Route 7, origin of National Route 102 and Aomori Prefectural Road 109 Hirosaki-Hiraka Line) Terminus: Minmaya Village, Higashitsugaru District, Aomori Prefecture (junction with National Route 280, terminus of Aomori Prefectural Road 230 Minmaya Station Line) Major transit points: Fujisaki Town, Minamitsugaru District, Aomori Prefecture; Goshogawara City; Nakasato Town, Kitatsugaru District, Aomori Prefecture Total length: 129.3 km (including overlapping sections) Overlapping length: 0.0 km Unopened length: None Actual length: 129.3 km Current road: 96.4 km Old road: 0.6 km New road: 32.3 km Designated section: Section overlapping with National Route 7 (Hirosaki City, Sports Park Entrance Intersection [origin] – Fujisaki Town, Minamitsugaru District, Funaba Intersection / National Route 339 Bypass Entrance Intersection)