We studied the diet of the raccoon dogs (Nyctereutes procyonoides) in the two urban parks by fecal analysis in winter, when their nutritional condition is important for breeding. From December 2015 to March 2016, we collected 39 feces from 14 latrines for defecation of raccoon dogs in the Shinjuku Gyoen National Garden (n = 31) and the Toyama Park (n = 8), located in central Tokyo. The samples were analyzed by the hand sorting method, and the frequency of occurrence for each food item was calculated. As a result, seeds (97.4%), birds (48.7%), and earthworms (48.7%) were detected as main food items. Major seeds of fruits detected were Hovenia dulcis (56.4%), Celtis sinensis (35.9%), Aphananthe aspera (25.6%), and Diospyros kaki (20.5%). These were planted tree species for gardens and urban greening. Preyed birds consisted mainly of Passeriformes (20.5%), Podicipedidae (7.7%), and Phalacrocoracidae (7.7%). Compared with other studies, fruits were main food items in not only urban parks but also other urban environments and mountain areas in winter. On the other hand, birds were more consumed in urban environments than mountain area, and therefore the availability of animal food items may be different between urban and mountain areas in winter.