The present study investigated the brain activity that accompanied motor inhibition before movement in human volitional finger movement. Seven individuals were instructed to press a force sensor with the right index finger. The time to begin this movement was indicated with a clock making a 4-s revolution. The time at which the clock hand passed the 3 o’clock position was adopted as the go-signal in the go task. In the series of trials, the task, we designated as prestop task, was performed with a red light-emitting diode stop-signal presented randomly at 0.1, 0.2, 0.3, 0.4, or 0.5 s before the go-signal. Cerebral potentials from the scalp were recorded using a 20-channel electroencephalography system. In the go task without the stop-signal, clear movement-related cortical potentials were observed. In the prestop tasks with the stop-signal, the participants were able to inhibit finger movement. A positive electroencephalography potential distributed at the midline frontocentral scalp 400 ms after the stop-signal was observed only in the prestop task. This suggests that the observed positive component is associated with the interruption of motor intent, as well as the revision of motor planning, in the motor cortices before the movement.