This study aims to examine the effect of the of audit committee effectiveness on the cost of equity. The study also examined the effect of the level of disclosure on integrated reporting on cost of equity. And test the effect of the audit committee effectiveness on cost of equity through the level of disclosure of integrated reporting, as a mediating variable. Audit committee effectiveness which is a corporate governance structure can be seen from the characteristics of activity, size and expertise and competence. The previous studies find that these characteristics are required to enable the audit committee perform better corporate governance. Hypothesis testing is carried out by using a structural equation modelling (SEM) model of 373 observations (firm-year) with the sample taken from more than 20 Organization for Economic Co-operation and Development (OECD) countries where the companies listed on The International Integrated Reporting Council (IIRC) during the period 2015-2017. The results of this study provide evidence that the level of integrated reporting disclosure reduces the company's cost of equity. However, the result for the influence of the audit committee effectiveness are still mixed. The findings indicate that the effectiveness of the audit committee does not affect the level of integrated reporting disclosure. And there is no significant influence between audit committee effectiveness, the level of integrated reporting disclosure and the cost of equity.