An angle sensing device includes a base, a rotation shaft, a detected target, and a proximity sensor. The rotation shaft is rotatably arranged on the base, and includes a side surface and a virtual axis. The detected target is arranged on the side surface, and an outer contour of a cross section of the detected target along a radial direction of the rotation shaft includes a first detected position and a second detected position, where a distance of the first detected position with respect to the virtual axis is different from that of the second detected position. The proximity sensor is fixedly arranged on the base and faces the detected target. When the detected target rotates together with the rotation shaft, the proximity sensor emits light toward the detected target and detects reflected light from the outer contour of the detected target to generate measurement data.