This study investigated how normative information on Facebook (i.e., the number of Likes on a Facebook post and a refuting comment) influences one's intention to share a rumor post regarding genetically modified foods. The results of an online experiment with 630 Facebook users showed that a high number of Likes increased the intention to share the post through perceived descriptive and injunctive norms of sharing behavior. The number of Likes on the post and a refuting comment interacted to influence perceived injunctive norms about rumor sharing. A comment stating that the post is a rumor increased injunctive norm perceptions about rumor sharing when the number of Likes on the post is low.