Purpose: To improve health guidance in Japanese-Brazilians living in Japan, we evaluated their diet and culture/ideas associated with their dietary habits. Methods : Ethnographic study. An interview survey, participant observation, and data collection in 14 Japanese-Brazilians were performed. Themes on the diet was extracted by data analysis. Results: Theme 1. In Brazil, the Japanese-Brazilians had a "Japanese-Brazilian diet," which was the mixture of Brazilian and Japanese diets. Theme 2: In Japan, the Japanese-Brazilians maintained the "Japanese-Brazilian diet" style with incorporation of foods and seasonings that agree with their working style and taste. The diet of the Japanese-Brazilians in Brazil markedly differed among individuals according to habits inherited from their parents/grandparents and surrounding environment. The Japanese diet in the Japanese-Brazilians was characterized by "rice and miso soup as a basis," "Brazilian and Japanese foods simultaneously served on the table," and "use of Japanese seasonings." The factors affecting the diet of the Japanese-Brazilians in Japan were "the frequencies of Japanese foods they had in Brazil," "the present life and working environment," and "Brazilian foods that can be purchased in their area", and "the purpose of visiting Japan." Discussion: "Japanese-Brazilian diet" originated in the Japanese food culture of Japanese immigrants in Brazil. Although Japanese-Brazilians working in Japan had held their own Japanese food culture, previous diversification of food culture in Japan forced them to adjust to modern Japanese food culture.