The online infomediary, playing an important role in e-commerce, provides more unbiased and refined product information than usual advertisement provided by online retailers. Interestingly, depending on its capability, the quality of product information is likely to differ. Also, given the fact that it enables consumers to grasp market price dispersion of products, the context of online infomediary is chance to investigating the effects of price dispersion. Despite the several previous endeavors that studied the existence of price dispersion in e-commerce, the reaction of consumers to price dispersion have not been investigated in a comprehensive way. This paper uses the elaboration likelihood model to explain how the level of involvement with a product moderates the impact of price dispersion and product information quality on consumer product attitude in online infomediary. A study conducted to test hypotheses has largely confirmed our expectations: (1) Interaction effects between involvement and price dispersion on consumer product attitude is significantly confirmed. (2) For low-involvement consumers, price dispersion of a product positively affects consumer product attitude, and for high-involvement consumers, it produces a negative effect, (3) Low-involvement consumers are affected by price dispersion rather than the quality of product information, but high-involvement consumers are mainly affected by price dispersion when the quality of the product information is low. These findings have implications for online infomediaries in terms of how to manage their users.