Japan National Route 166

{{short description|National highway in Japan}}

{{Infobox road

|country=JPN

|type=National

|route=166

|maint=

|alternate_name=

|map={{Maplink2|zoom=7|frame=yes|plain=yes|frame-align=center|frame-width=300|frame-height=300|frame-latitude=34.48|frame-longitude=135.99|type=line|stroke-color=#cc0000|stroke-width=2}}

|map_custom=yes

|image=Yokooji, Ise-honkaido01.jpg

|length_km=125.4

|length_round=

|length_ref={{cite web|title=一般国道の路線別、都道府県別道路現況|trans-title=Road statistics by General National Highway route and prefecture|url=http://www.mlit.go.jp/road/ir/ir-data/tokei-nen/2016/pdf/d_genkyou26.pdf|language=ja|publisher=Ministry of Land, Infrastructure, Transport and Tourism|access-date=19 February 2020}}

|established=18 May 1953

|direction_a=West

|terminus_a= {{jct|country=JPN|Route|170}} in Habikino, Osaka

|junction=

|direction_b=East

|terminus_b= {{jct|country=JPN|Route|23}} in Matsusaka, Mie

|previous_type=Route

|previous_route=165

|next_type=Route

|next_route=167

|browse=

}}

National Route 166 is a national highway of Japan connecting Habikino, Osaka and Matsusaka, Mie in Japan, with a total length of 125.4 km (77.92 mi).