In this article, the influence of different reference electrodes on the scalp distribution of event-related potentials (ERPs) was evaluated. The search-related negativity (SN) is one of negative ERP component which varies with memory and display load in a visual search task. The amplitude and topography of SN were sensitive to the selection of reference site. The effects of memory and display load at frontal and temporal sites were larger when ERPs were referred to tip of nose compared with linked-ear reference. In contrast, the attenuation of N400 due to semantic relation between word pairs was almost invariable with use of different reference sites. These results suggest that optimal reference electrode selection depends on what component of ERPs is a research target, and has to be evaluated not only theoretically but also empirically.