Cause-Related Marketing (CRM) has emerged as a new concept that links CSR activities to marketing, enabling corporations to pursue both building company-consumer partnership and gaining sustainable mutual benefits that are elicited from the partnership. Among various cause-related marketing activities, on-line cause-related advertising is the most commonly used one. The purpose of this study is to examine the effects of on-line cause-related advertising and moderating role of ethical consumption propensity. In particular, this study intends to contribute to successful development of on-line cause-related advertising strategy by focusing on the relationship between the four factors: customers' perception of on-line cause-related advertising, brand-consumer relationship, brand attachment and loyalty. The results of this study are as follows: First, customers' perception of on-line cause-related advertising was related positively to consumer-brand- relationship. Second, brand-consumer relationship was related positively to brand attachment and customer loyalty. Third, brand attachment was related positively to customer loyalty. Furthermore, from the consumer’s psychological viewpoint, ethical consumption propensity had a significant moderating effect to between customers' perception of cause-related advertising and brand-consumer relationship as well as brand attachment. The results of this study may contribute to the existing literature as an new empirical attempt to examine the effect of the on-line cause-related advertising.