The Hokkaido at-large district is a constituency of the House of Councillors in the Diet of Japan (national legislature). It consists of the prefecture (dō) of Hokkai[dō] and is represented by six Councillors electing three at a time every three years by single non-transferable vote for six-year terms. In the election period from 2019 to 2022, Hokkaido's Councillors are (party affiliation as of September 2019):
After the House of Councillors had replaced the House of Peers according to the constitution of 1947, Hokkaido was represented by eight Councillors. In the early years of the 1955 System, all four seats went to the two major postwar parties, the Liberal Democratic Party (LDP) and the Japan Socialist Party (JSP). But smaller parties such as the Japanese Communist Party (JCP) had a chance to pick up seats in Hokkaido as the vote share sufficient to gain a seat was often significantly below 20 percent. The high number of candidates increased the risk of vote splitting for the major parties: In 1974, two incumbent LDP candidates and conservative independent Tatsuo Takahashi ranked 5th, 6th and 7th leaving all four seats to the center-left to left opposition parties Kōmeitō, JSP and JCP.
In a major reapportionment in 1994 the number of Councillors from Hokkaido was halved to four. It became effective in the 1995 and 1998 elections. During the period as two-member district, Hokkaidō usually split seats evenly between opposition and ruling parties like most two-member districts – although the Democrats unsuccessfully aimed for both seats in the 2004, 2007 and 2010 elections. In another 2015 reapportionment, effective in the two classes from the 2016 and 2019 elections, Hokkaidō's representation in the upper house was raised to six.
Decimals from anbunhyō ("fractional proportional votes" from ambiguous votes) omitted; note that the rounded whole numbers may still include fractions of numbers >2 of ambiguous votes and do not necessarily represent "whole" voters
(2016 only) (*): ineligible as runner-up replacement (kuriage-tōsen), lost deposit
^"総務省|令和4年9月1日現在選挙人名簿及び在外選挙人名簿登録者数" [Ministry of Internal Affairs and Communications - Number of registered voters as of 1 September 2022] (in Japanese). Retrieved 2023-01-04.
^参議院>第1回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第2回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第3回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第4回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第5回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第6回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第7回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第8回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.
^参議院>第9回参議院議員選挙>北海道選挙区. senkyo.janjan.jp ザ・選挙 (in Japanese). Heartbeats. Retrieved 2013-04-03.