This study collected negative events assumed when people procrastinate, classified these negative events, and examined the relationship between types of negative events and emotions. In the pilot study, we collected negative events that were assumed when people procrastinate. The 28 items included events related to stress and to the performance of the tasks. In Study 1, we intended to select and classify the negative event items. The participants were asked how strongly they had thought that these negative events actually happen. The exploratory factor analysis showed that the negative events did not fall into multiple categories. In Study 2, participants were asked how they were concerned by 28 negative events. As in Study 1, the exploratory factor analysis showed that the negative events did not fall into more than one category. The participants were also asked about emotions in the procrastination process. We examined the relationship between those emotions and the level of concern for negative events. A positive correlation was found between “negative emotions” and “optimism about the situation” and the degree of concern about negative events during the procrastination process. These results indicate that the degree of concern is more important than the type of negative event, and that the degree is related to the occurrence of negative emotions during the procrastination process.