Abstract. The present paper addresses a general diagram to investigate the real-time parallel computation mechanism in the brain, using an idea of “Gantt chart.” This diagram explicitly represents the temporal relationship between the computations running in various functional modules in the brain, and helps us to understand how the brain computation proceeds along the time. The author illustrates how we can utilize this diagram, taking a motor planning model of reaching movement as an example. Moreover, the author discusses the mechanism of intra- and inter-module computations on this diagram and addresses a tentative view that can explain the relationship between the movement variability and reaction time.