With the advance of automation in recent years, the interaction between systems and users has become less intense and more monotonous. Thus, there is some concern that the arousal level of users is liable to decrease while interacting with a system. The decrease in the arousal levels of users causes drowsiness in their bodies and deterioration of their performance, potentially leading to serious accidents. Thus, it is necessary to establish a method for maintaining arousal level. At present, external-stimulation methods such as sounds or vibrations are popular; on the other hand, some psychophysiological studies have suggested a relationship between motivation and arousal, but there has been little research on how to apply these studies, as well as only a few examples of practical application. Therefore, in this research, we propose and verify a method for maintaining arousal by inducing intrinsic motivations. This arousal maintenance was found to work well during manual operations, but to be less effective by influence of stress during automatic operations. In addition, the varieties of presentation of feedbacks and the arousal level during operations were found to be influenced the effectiveness.