The purpose of the present paper was to determine error-monitoring ability and its relationship with executive function in patients with schizophrenia. In order to evaluate error-monitoring ability, the error negativity (Ne) and error positivity (Pe) were measured using the Stroop task. The correct-related negativity (CRN) and positivity (Pc) were also measured. In addition, neuropsychological tests were administered in order to evaluate executive function. The patients with schizophrenia had significantly reduced Ne and augmented CRN amplitudes, but the Pe and Pc amplitudes of the patients were comparable to those of the controls. In addition, the Ne amplitude, measured at Fcz was positively correlated with the Trail Making Test (TMT), part B response time, and the categories achieved on the Wisconsin Card Sorting Test (WCST) in patients with schizophrenia. No significant correlations were found between Ne amplitude and performance on the neuropsychological tests in the controls. And no associations were detected between CRN, Pe, Pc amplitudes and neuropsychological performance, in either the patients with schizophrenia or the controls. Reduced Ne amplitudes and augmented CRN amplitudes in patients with schizophrenia suggest the dysfunctional behavior-monitoring system in these patients. The functional significances of Ne and Pe are discussed.