Many previous studies using motor tasks with a backward masking paradigm have shown that participants can provide a motor response to a given stimulus, even when they do not consciously perceive it. For the backward masking paradigm, 2 stimuli are presented with a short temporal gap in between so that the conscious perception of the first (prime) stimulus is masked by the second (mask) stimulus. In the present study, we examine the nature of the visual and motor information processing of visual inputs derived from the prime stimulus when conscious perception is prevented by a second, masking stimulus. We measured reaction times (RTs) in a simple RT task with a backward masking paradigm. We also measured event-related potentials (ERPs), P100 and P300, and both the stimulus-locked (S-LRP) and response-locked (R-LRP) lateralized readiness potentials, which reflect activity in the motor cortex contralateral to the response hand. Our results showed that RT, latency of P100, and latency of S-LRP, were shorter for backward masking conditions (i.e., those where a prime plus a mask stimulus were presented) than for a mask stimulus-alone condition. This suggests that both perceptual (P100) and motor-related (S-LRP) information processing is affected by inputs from the prime stimulus even when it was not consciously perceived. Subsequent simple and partial correlation analyses showed that RT in backward masking conditions was more closely correlated with S-LRP latency than P100 latency, suggesting that the shortening effects on RT under backward masking conditions were likely mediated by facilitation/advancement of motor rather than visual, information processing.