This study examined intergenerational interaction and motivations for participation among younger and older adults in Japan. Participants included 450 younger adults (275 males, 175 females; ages 25-39 years, M = 34.08, SD = 3.91) and 450 older adults (275 males, 175 females; ages 70-84 years, M = 74.50, SD = 3.53). Measures included frequency of intergenerational conversations and activities, perceived friendliness and comfort during intergenerational interactions, motivation for intergenerational contact, and the Interpersonal Orientation Scale (IOS). Results indicated that 58.9% of older adults reported no opportunities for interaction with individuals in their 20s and 30s, while 55.6% of younger adults had no opportunities for interaction with individuals in their 70s and 80s, reflecting a general lack of intergenerational exchange. Stepwise multiple regression analyses were conducted with the frequency of intergenerational conversations and activities as the dependent variable and motivations and affinity for others as predictors. For interactions with younger adults, both groups were primarily motivated by positive emotions, such as enjoyment, warmth, vitality, and satisfaction derived from contact. For interactions with older adults, in addition to the aforementioned positive emotions, both groups valued the consolation and support gained through conversation. These findings suggest that, while opportunities for intergenerational interaction remain limited, motivations for participation are shared across age groups.