At the merging point, vehicles on the main road must reduce their velocity to avoid slow merging vehicles from a branch road, which leads to a traffic jam. Some researchers point out the effectiveness of a zipper merging pattern for improving the traffic near the merging point. In this study, the authors discuss the effectiveness of a zipper merging pattern using cellular automata simulation. Firstly, the single and multiple vehicle following models are defined. The stability analysis of the models then gives the parameters. In the simulation, two merging patterns are compared. In the non-zipper merging pattern, two vehicles merge continuously from a branch road. In the zipper merging pattern, two vehicles merge between main road vehicles. The results show that the zipper merging pattern is more effective than the non-zipper merging pattern for reducing the traffic jam near the merging point.