Some authorities have highlighted information relating to the abuse liability of tobacco products as key in reaching regulatory decisions. Although abuse liability should be assessed with multiple factors, one of the essential elements is the subjective effects of product use. In this study, we conducted a preliminary assessment to characterize some subjective effects during short-term use of a recently developed novel tobacco vapor product (NTV). The measurements were taken as part of a five-day, single center, randomized, open-label study with healthy adult Japanese smokers to assess exposure to selected smoke constituents after switching from conventional cigarette to NTV use (UMIN000025777). Each of the 20 participants who switched to NTV use (NTV group) or who continued to smoke their own brand of conventional cigarettes (CC group) were asked to complete measurements of subjective effects including product liking, satisfaction, smoking urges and withdrawal over the five-day period. Patterns of consumption and topography were also measured. Overall scores for liking, satisfaction, reduction in smoking urges and reduction in withdrawal in the NTV group did not exceed those observed in the CC group. Nevertheless, during the study period the scores for liking, consumption and number of puffs gradually increased in the NTV group but remained stable in the CC group. In conclusion, the subjective effect assessments included in this short-term study would suggest that the abuse liability of NTV would not exceed that of conventional cigarettes. However, the increase in the liking score, consumption and number of puffs during NTV use may reflect a course of adaptation to NTV use among participants who have not previously been familiar with tobacco products other than conventional cigarettes. Therefore, it remains to be assessed how such outcomes could change over prolonged observation.