The subject is a rotary drive device (1), which has a device housing (7) in which drive means (2) are disposed that are in driving communication with a rotatably supported power takeoff part (4). The power takeoff part (4) has a power takeoff disc (5) that is received at least partly in a bearing receptacle (25) of the device housing (7), the power takeoff disc being surrounded by an annular roller bearing unit (33). The roller bearing unit has a bearing assembly (34) with rolling elements (35) and with one inner and one outer running surface arrangement (37, 38), and the entire bearing assembly (34) is disposed inside the bearing receptacle (25) and is surrounded radially outward by a boundary wall portion (27) of the device housing (7).