An angle sensing device including a first object, a second object, a magnetic field source, and a first magnetic sensor is provided. The second object is adapted to be rotated with respect to the first object, so that an inclined angle of the second object with respect to the first object is changed. The magnetic field source is connected to the second object. The first magnetic sensor is connected to the first object, and configured to sense a magnetic field generated by the magnetic field source. When the second object is rotated with respect to the first object, the magnetic field sensed by the first magnetic sensor changes, so that an output signal of the first magnetic sensor corresponding to the magnetic field changes.