An automatic roller shade includes a shade body rotatably mounted to between a first and a second mounting bracket; a stop mechanism mounted in an end of a roller of the shade body; and a driving mechanism mounted in another opposite end of the roller. The stop mechanism includes a winding element connected to the roller and a spiral spring element having an end connected to the winding element. The spiral spring element enables a balance between a force for lifting or winding a shade fabric of the shade and the gravitational force lowering or unwinding the shade fabric. The driving mechanism at the other end of the roller can adopt a micro motor as a power source and the micro motor can be invisibly located inside the roller, enabling the automatic roller shade to have reduced power consumption and manufacturing cost while having a compact and esthetic appearance.