Abstract: An engaging device for a computer screen in a car, comprises a fixing base fixedly attached in the car, lock block, and a coupling frame attached to the rear side of the computer screen. The lock block is rotatably engages with the fixing base by way of two pivots. The pivots have a function of stagnating the lock block at specific angular position optionally. Both lateral sides of the coupling frame have a locking hole respectively and the lock block at both lateral sides thereof provides an elastic engaging plate therein. The respective elastic engaging plate has a part extending outward through the locking hole. Once the lock block is inserted into the coupling frame, a detachable firm engagement between the lock block and the coupling frame can be reached substantially.