This study used the event-related potential technique to explore the neural correlates of outcome evaluation about helping others during a decision task. The results showed that the amplitude of feedback-related negativity elicited by 'failed outcome' (indicating a failure in helping others) was larger than that elicited by 'successful outcome' (indicating a success in helping others). Failed outcome also elicited a larger and longer P300 than successful outcome. The feedback-related negativity and P300 reflect the automatic process in an early stage and the control process in a late stage of outcome evaluation, respectively. Accordingly, these event-related potential results have shown the time course of outcome evaluation about helping others, and suggest that brain response to outcome information of helping others is generally similar to those in economic decision tasks.