Because obsessive-compulsive disorder (OCD) is a highly impairing and often chronic psychiatric disorder, there is high interest in novel add-on or alternative intervention approaches. The error-related negativity (ERN), a response-related ERP occurring shortly after incorrect responses, might provide a promising target for novel interventions. Increases in the ERN have been reliably shown in OCD and are viewed as an important biomarker for the disorder. The ERN has been functionally associated with a heightened response to errors as negative, potentially harmful events. Attention Bias Modification (ABM) may be one promising strategy to reduce the ERN. Thus, in the current study, we used ABM training with the aim to reduce the threat value of errors and thus the ERN in OCD. Participants with OCD (n = 23) and healthy participants (n = 24) performed a 20-minute probe detection task in a condition that trained to attend to neutral and away from negative stimuli, while another group of healthy participants (n = 24) performed a sham version of the training. Results indicated a significant reduction of initially increased ERN amplitudes in the OCD group after the training, whereas in both healthy subgroups no significant changes in ERN were observed, resulting in non-significant group differences after ABM. These results indicate that ABM training may be a viable intervention to reduce ERN in participants with increased error-signaling, as in OCD. The current study serves as a clinical pilot investigation for future studies needed to elucidate underlying mechanisms, clinical effects and long-term outcome.