The aim of this study was to identify the psychological mechanism between smartphone use during off-job time (smartphone use) and job attitudes (emotional exhaustion, job engagement). For this purpose, a questionnaire survey was conducted for 381 employees. The results of this study showed that smartphone use had a positive indirect effect on emotional exhaustion through emotional rumination and had a positive indirect effect on job engagement through problem-solving pondering. And the indirect effects of emotional rumination were relatively strong. In addition, the indirect effect of emotional rumination was found to increase more as the segmentation preference of the worker increased. Considering the work environment in which the segmentation preference of the worker is expected to increase as work-life balance is emphasized gradually, the effect of smartphone use through emotional ruminations on emotional exhaustion or job engagement will be increase. Based on these results, the implications of the study were discussed and future research directions were suggested.