This study examines the association between multitasking and time pressure using time-use data collected by the experience sampling method (ESM) in Japan. Time pressure is the degree of temporal (time-related) stress that motivates people to complete necessary tasks in their daily lives, and multitasking refers to how one simultaneously engages in several tasks and activities. By utilising a probability-based sample with ESM, this study examines the multitasking effect using fixed effects models and addresses issues of retrospective errors and unobserved time-constant individual heterogeneity. The use of fixed effects regression models revealed that although multitasking, which is defined as the number of simultaneous activities taking place in one hour, does not influence subjective time pressure in its entirety, it heightens time pressure after controlling for the activity types in each time slot. This study considered differences in gender and survey dates, as well. Although we did not find any gender heterogeneity, the multitasking effect was apparently salient for women. Furthermore, multitasking increases time pressure, particularly on weekends. One explanation is that respondents must concentrate their time on a single task (paid work) on weekdays. Accordingly, the loading of each activity should affect one’s subjective time pressure. However, on weekends, people are exposed to more multitasking situations since they have more discretionary time and have to think more about how to spend their time compared to weekdays. Finally, based on its results, this study proposes an agenda for future research.