Abstract
The merged constituencies which combined Tottori and Shimane prefectural constituencies and Tokushima and Kochi prefectural constituencies, has been applied for the first time since the 2016 upper house election, and negative effects on electoral process and voter turnout in those districts has been seen in that election. In this paper, I focused on turnout change from previous elections in the Tottori and Shimane prefectural constituency. I analyzed the data aggregated in each municipalities which also includes Okayama and Yamaguchi electoral districts, where the single-member district as well as the Tottori and Shimane constituency in the same Chugoku region but the combination of constituency was not applied. I found that turnout in municipalities in Tottori and Shimane had still been in a higher level, but the application of merging constituencies brought about the negative effect, which was remarkable in Tottori district, on turnout change since last upper house election.
