<h3>Background</h3> The coronavirus disease 2019 (COVID-19) pandemic has greatly affected employment and the work environment. Socioeconomic status is known to affect dietary habits. <h3>Objective</h3> To examine the associations between changes in household income and changes in diet, dietary behavior, and lifestyle. <h3>Study Design, Settings, Participants</h3> A cross-sectional questionnaire survey was conducted via the Internet in November 2020. The participants were 6,000 Japanese men and women (aged 20–64 years old) who were registered with a research company. After excluding participants with invalid responses, a total of 5,158 participants were included in the analysis. <h3>Measurable Outcome/Analysis</h3> The questionnaire included the following items: demographic characteristics; socioeconomic status; and changes in household income, diet, dietary behavior, and lifestyle since before the COVID-19 pandemic (November 2019) to the present (November 2020). Changes in household income and demographic characteristics and socioeconomic status were compared using the χ2 test. The association between changes in household income and dietary habits was examined by multiple logistic regression analysis. <h3>Results</h3> Household income had decreased for 1,144 participants (22.2%). In this group, a high proportion were in their 50s, were high school graduates, and had household income under 2 million yen in 2019. Decrease in household income was negatively associated with vegetable intake, frequency of eating out, time spent on breakfast, and time spent exercising, and positively associated with frequency of drinking and time spent on lunch. <h3>Conclusion</h3> The results of this study suggest that decrease in household income during the COVID-19 pandemic was associated with expansion of economic disparities and changes in dietary habits, such as vegetable intake and mealtimes.