A slippage-preventing device for tubular jack handle consists of a jack handle stand that is provided with a movable bar extending into the inner wall of an insertion hole therein. A tubular handle has a front end, which is provided with a locking groove and an angled-rim tip. As the tubular handle is inserted into the insertion hole, the angled-rim tip at the front end firstly pushes the movable bar aside, and as the insertion is completed, the movable bar is driven back resiliently to lock the tubular handle at the locking groove thereon. The locking mechanism can be removed by pulling outward the movable bar. This mechanism facilitates the assembly and disassembly of the tubular handle and the jack handle stand.