Internal meshing planetary gear device and joint device for robot

The invention provides an internally engaged planetary gear device and a joint device for a robot, which are capable of limiting axial movement of a crankshaft despite a relatively simple structure. The internally engaged planetary gear device (1B) is provided with an internally toothed gear (2), a planetary gear (3), a crankshaft (7A), and at least one crankshaft bearing. The crankshaft (7A) swings the planetary gear (3) by rotating about the axis. At least one crankshaft bearing supports the crankshaft (7A). The at least one crankshaft bearing restricts the movement of the crankshaft (7A) in at least one side in the axial direction in a state in which a preload is not applied at least in the axial direction along the axial center.