Provided is a roller bearing device, which is suitable for preventing misdetection of a rotation sensor when a moment load is applied. A thin motor 100 includes a cross roller bearing 14 having an inner ring 14a and an outer ring 14b, a stator 22 supported by the inner ring 14a, a rotor 12 supported by the outer ring 14b, a motor unit 16 that applies rotation torque to the rotor 12, and a resolver 30 that detects a rotation angle position of the rotor 12. The resolver 30, the cross roller bearing 14, and the motor unit 16 are arranged in the recited order from the radially inner side on a radially identical plane.