Event-related potentials (ERPs) were recorded during the evaluation of the appropriateness of cooperative actions between two people. We used pictures of pass-and-receive actions as one type of cooperative actions, in which one person passed an object and another reached out to receive it with a preshaped hand. Eleven participants judged whether the receiving actions were appropriate or inappropriate in relation to the passing ones. The inappropriate actions elicited a widely distributed and parietal maximum N400 as compared with the appropriate ones. These results suggest that the N400 is evoked in the incongruous context in which two people perform inappropriate cooperative actions and is related to the semantic processing that involves the prediction of interpersonal action sequences.