The activities of predators and prey have been reported to influence each other. However, few studies have clarified when African leopards Panthera pardus are likely to encounter their prey. One reason for this is that the activity patterns of African forest mammals are poorly understood. Therefore, I aimed to clarify the activity patterns of leopards and their prey species by deploying camera traps on the ground and in trees in Mahale Mountains National Park, Tanzania. In total, 4468 camera days of camera traps set on the ground and 286 camera days of camera traps set in trees were analyzed. The overlap in activity patterns between leopards and their main prey species was calculated using coefficient Δ. At least seven leopards were identified in the study area. Leopards were active throughout the day, with crepuscular peaks at dawn and dusk. Blue duikers Philantomba monticola, the most consumed species in Mahale, were predominantly diurnal. The activity patterns of leopards moderately overlapped with those of blue duikers (Δ = 0.65). The activity patterns of leopards showed a moderate (Δ = 0.61) or low (Δ = 0.42) overlap with those of red‐tailed monkeys Cercopithecus ascanius when detections were captured by arboreal or terrestrial cameras, respectively. Mahale leopards may hunt blue duikers and arboreal primates in the midday on the ground, and may also attack primates in roost trees at night. Future studies on the leopard diet in various study areas, as well as comparisons of activity patterns between leopards and other animals, will elucidate leopard ecology.