Real time object tracking method on video sequence is important technology for robot vision, security systems using visual information, etc. We propose an object tracking algorithm using Particle Swarm Optimization (PSO) technique, which is an optimization method inspired by swarm behaviors. In PSO algorithm, each particle (individual) belonging to the swarm searches optimal solution efficiently using entire swarm information. In this paper, we propose an effective object tracking technique in a wide expanse of search range by applying PSO for searching a moving object in the video image sequence. We demonstrate the effectiveness and practical utility of our method through some simulations and experiments.