Fatigue is a health problem prevalent in modern societies. Fatigue sensation plays an important role as a biological alarm urging rest to maintain homeostasis, and clarifying the neural mechanisms related to fatigue sensations by which we decide to engage in rest is therefore essential. This study enrolled healthy male volunteers and showed that the decrease in alpha-band power as assessed by magnetoencephalography of the left Brodmann's area (BA) 6 before perception of fatigue when a button-press based on the level of fatigue was required was smaller than that before perception of the intention to move when a voluntary button-press was required. In addition, the decrease of alpha-band power in the left BA 6 before the perception of fatigue was not altered compared with that in the right BA 6 when a button-press based on the level of fatigue was required. These results suggest that the button-press based on the perception of fatigue is not prepared before the perception of fatigue. These findings will advance the understanding of the neural mechanisms related to subjective feelings such as fatigue sensation.