Any such system is disclosed in Japanese Patent Laid Open Publication No. 58-193510, among other sources. It's a further object of the current invention to offer such a sun tracking device can cut back the drive energy requirements for driving the rotatable table to an especially low level, and might help and drive the rotatable table with a easy structure. FIGS. 4(a) to 4(c) are illustrative drawings for describing the solar tracking action of the primary most well-liked embodiment sun tracking device. FIG. 5 is a aspect view thereof. FIGS. 6(a) to 6(c) are plan view for illustrating the solar tracking motion of the second most well-liked embodiment sun tracking device. FIG. Eight is a plan view thereof. FIG. 9 is a side view thereof. FIG. 10 is a plan view showing a solar power generating system which contains a fifth preferred embodiment of the sun tracking device based on the present invention.