We applied high resolution event-related potentials (ERPs) to assess brain activities associated with inhibition of irrelevant information processing during auditory selective attention. Ten healthy subjects performed an auditory selective attention task. ERPs in response to standard stimuli delivered to the unattended ear (irrelevant stimuli) and those delivered to the attended ear (relevant stimuli) were evaluated using temporally sequential scalp current density (SCD) mappings. For the irrelevant stimuli, current sources were located in the mid-frontal regions at 140-220 ms post-stimuli, and these SCD values were significantly larger than those for the relevant stimuli. These results suggest that auditory selective attention process involves not only focusing attention on relevant information, but also inhibitory processing of irrelevant information mediated by the frontal cortex.