The present study examined the effects of tasks involving different numbers of processes on working memory (WM) by conducting cognitive function tests and using NIRS (near-infrared spectroscopy). The subjects were asked to perform two types of task involving varying numbers of processes. After the subjects performed both tasks involving one and multiple processes: drawing and the creation of a box, respectively, the oxygen hemoglobin concentration in the DLPFC was higher. However, there was no significant difference between the two tasks. The results of cognitive function tests following the production of boxes were also compared, and the PASAT 2 sec and SDMT scores were significantly higher. These results suggested that the efficient implementation of the task involving multiple processes generated an appropriate level of cognitive load required to promote the active functioning of WM and, as a result, the subjects achieved higher cognitive function test scores after completing the tasks.