The aim of this study is understanding the interaction occured during driving training. In driving trainings driving operations and utterances occur sequentially in a closely related way. So this study analyses the sequence as the interaction between participants involving driving operations. A videotaped data recorded inside a car when the driving training was going on. In the data there are two participants: the trainee and the supporter. This study focuses on the scene of slope starting training. The concrete questions is as follows: 1. What interaction is done in the driving training. 2.What the interaction achieves in the driving training. The results are below: When a trial of slope starting has failed, the trainee declares that the trial is a failure and describes what the failure is like before the supporter says something related to the trial. This indicates that during the driving training trainee has to certificate the understanding on what has to be understood by a driver. The declaration and description of failure as early as possible is a certification of the understanding.