Embedded systems use NAND flash memory as a secondary storage device because it has many attractive features such as small size, fast access speeds, shock resistance, and light weight. NAND flash memory based embedded systems exploit a "demand paging" to run applications and also use a "swapping" to extend a limited main memory space. Because the embedded systems use NAND flash memory as swap space, it should perform garbage collection, which is a time-consuming operation. Besides, the number of the erase operations allowed to each block is also limited. In this paper, we propose a new garbage collection policy for embedded systems with the swap system. The proposed garbage collection policy focuses on minimizing the garbage collection time and even wear-leveling. Trace-driven simulations show that the proposed policy performs better than existing garbage collection policies in terms of the garbage collection time and the endurance of flash memory.