With the rapid innovation of online services, people come to social communities not only to connect with their friends but also to share their feelings, ideas and information. Hence, these social communities have become a powerful platform for information sharing and product marketing. The purpose of this study is to examine the factors that affect the intention of information sharing in social communities. This study investigates the influence of user motivation and the attributes of message. An online survey was conducted. The result indicates: (1) In social communities, the quality of the message (i.e., the degree of credibility and level of irritation) was the major concern for them to decide whether to share the message with their friends. We find that intrinsic motivation has no significant effect on the intention to share. This is different from some previous literature. (2) Different attribute were having effects when the nature of the message differs. Content enjoyment was the most influential factor in recommending entertainment messages. Source creditability was the major factor for knowledge-type messages. When they share economic-type messages, the effect of message-related attributes were similar to that of the knowledge-type message, except that the competence of the intrinsic motivation became significant. This indicates that the subject must feel competent in evaluating the economic message in order for them to share with peers.