Embedded software’ s scale is getting larger and larger these days. In this situation, it is difficult to grow young software developers’ design skill with OJT (on-the-job-training) because there are less opportunities to make software from scratch. We have participated in ET Robocon (ET software design robot contest) for six years as a chance that young developers gain software development experiences from scratch. Many young developers attended this contest in our company and they grew not only their design and modeling skills but also motivations with this contest. This paper describes our activities toward the contest and the educational effects of this activities.