Improving the transparency of corporate information disclosure is a key principle of corporate governance in Taiwan. This study uses the information disclosure assessment system established by the information disclosure and transparency ranking system to explore whether information transparency can reduce the degree of mispricing. The study uses the data of 10,686 listed companies in Taiwan for the period from 2005 to 2014. We find that a higher information disclosure ranking (IDR) of rated companies corresponds to a more substantial reduction in the degree of mispricing. Moreover, we discover that product market competition affects mispricing in that smaller degrees of mispricing reflect greater exclusivity; this suggests that lower industry transaction and competition costs lead to less substantial mispricing. Finally, we observe that the effect of information disclosure score on the degree of mispricing is lower in more exclusive industries. Furthermore, a regression process using instrumental variables reveals that IDRs have the significant effect of reducing the degree of mispricing.