We trained business ability of the students through the senior instructing younger student system by fourth year students in the class of the practical skill. The theme of the practical skill is the resolution and the assembling of the gasoline engine, the automatic control of the radio control car with the PLC, the learning of dynamics using Mini-Yonku and the operation of the laser cutter. For the fourth students, we can expect an effect of their ability in the future work. For the first students, we can expect an effect for them to be interested in mechanical engineering. Concerning the effects of this project, all the fourth students and teachers discussed, and the effect of the project was evaluated by a poster session. As a result, we have found that more effects than we had expected has been gained.