In this review I introduce the literature concerning variations in the feeding ecology of wild Japanese macaques (Macaca fuscata), for which many Japanese primatologists have collected data for more than 60 years. Specifically, I review 1) temporal, 2) spatial, and 3) inter-individual variations in the feeding ecology of the macaques. Food resources of the macaques in habitats exhibit temporal shifts (in short-term, seasonal change, and inter-annual change), which consequently affect feeding-related behavior, such as ranging patterns, activity budgets, and degree of crop-raiding. On the other hand, temporal changes in feeding sometimes affect inter-specific relationships. Food environment differs regionally, which is attributed to forest productivity and flora, and/or physical conditions such as temperature and snowfall. The feeding ecology differs even between neighboring troops inhabiting different forest structures. A troop of macaques consists of males and females of different ages and social ranks whose nutritional demands vary. Such inter-individual variation within group affects their feeding ecology, which consequently affects population parameters through competition over food resources. Variation in food habits would affect other ecological phenomena, such as seed dispersal and plant community structure. Finally, I discuss several challenges facing future studies of the feeding ecology of Japanese macaques.