ObjectivesThe aim of this study was to investigate the association of living condition (deprivation and urbanisation level) with loneliness and social isolation.Study designCross-sectional study.MethodsData were retrieved from the Japan COVID-19 and Society Internet Survey, a nationwide online cohort study, conducted from September to October 2021. Area Deprivation Index and Densely Inhabited District data were used as indicators of living condition. The Japanese version of the University of California, Los Angeles Loneliness Scale and Lubben Social Network Scale-6 were used to assess loneliness and social isolation, respectively. Analysis of covariance was performed to compare the difference in outcome variables by living conditions (four categories), adjusting for gender, age, educational attainment, income, marital status, people living with, work status and subjective health status.ResultsA total of 27 520 community dwelling people were included in this study. For loneliness, living condition did not show a significant difference in the adjusted model, while deprived area had a tendency to show high loneliness. For social isolation, there was a significant group difference in the adjusted model (p<0.001), and living in a higher urbanisation level and lower deprivation showed the highest score for social isolation.ConclusionOverall, the effects of the living condition on loneliness and social isolation were small. Further study is needed to explore more comprehensive environment factors affecting loneliness and social isolation.