Individuals can observe the occurrence of mind wandering (task-unrelated thought) while doing an important task and stop it. This study examined whether mind wandering is detected through the monitoring process requiring attentional resources. In the first task, participants read a short story, where the constituent words were presented one-by-one and the next word appeared by pressing a key. The reading time for each word was measured. As a secondary task, one group reported the occurrence of mind wandering each time they noticed it during the reading. The other group performed a prospective memory task (detecting target words) that required attentional resources, and the control group performed only the reading task. The result showed that while performing the prospective memory task increased the mean reading time, the reporting of mind wandering did not influence it. This finding suggests that the detection of mind wandering did not require attentional resources.