This study investigated the effect of the presence of other person on cognition, emotion, and aggressive behavior elicited by media violence. In experiment 1, sixty undergraduate students (30 males and 30 females) were first exposed to a violent video either with the same-gender person or alone. Then, subjects described what they were thinking about while watching the video, and rated their affect about the video. Heart rate and eye blink rate were recorded continuously while watching the video. Results showed that the presence of other person while exposed to media violence inhibited negative affect and facilitated positive thoughts and affect. In experiment 2, sixty undergraduate students (30 males and 30 females)were exposed to a violent video either with the samegender person who reacted positively to the video or with the one who reacted negatively. Unlike the experiment 1, aggressive behavior was measured on the Taylor (1967) paradigm. Results showed that the presence of other person who reacted positively to media violence facilitated aggressive behavior.