We explored the association between the motivation for and effects of cooking class participation in disaster-affected areas following the 2011 Great East Japan Earthquake and Tsunami. We conducted questionnaire surveys in January and February 2020, and applied three Poisson regression models to a cross-sectional dataset of participants, analyzing three perceived participation effects: increase in new acquaintances and friends, increase in excursion opportunities, potential for gaining motivation, and a new sense of life purpose. We also applied the interaction term of motivation variables and usual eating patterns (eating alone or with others). We obtained 257 valid responses from 15 cooking venues. The interaction term for participants’ motivation and eating patterns was associated with their perceived participation effects. “Motivation for nutrition improvement × eating alone” was positively associated with an increase in new acquaintances and friends (IRR: 3.05, 95% CI, 1.22–7.64). “Motivation for increasing personal cooking repertoire × eating alone” was positively associated with increased excursion opportunities (IRR: 5.46, 95% CI, 1.41–21.20). In contrast, the interaction effect of “motivation of increasing nutrition improvement × eating alone” was negatively associated with increased excursion opportunities (IRR: 0.27, 95% CI, 0.12–0.69). The results show that the cooking class was effective, as residents’ participation improved their nutritional health support and increased their social relationships.