Indonesia Stock Exchange (ISE) in 2012 recorded that there were 36.6% of companies that did not meet the timeliness reporting in preparing the financial statements, whereas companies that implement Good Corporate Governance (GCG) should be timely in preparing the financial statements as the implementation of the principle of transparency which is one of the principles of GCG. This study aims to examine how the role of GCG in monitoring and suppressing the timeliness reporting in preparing the financial statements and whether there are differences in market reaction between the companies that meet the timeliness reporting and which do not. The research samples taken from population members were 96 companies listed on Indonesia Stock Exchangein 2013. The data processed by using logistic regression and independent test. The results show that the institutional ownership, independent board and audit committee play a role in the fulfillment of timeliness reporting while the management ownership and board size have insignificant. Further results of the study showed no difference in reaction to the market on the company meet and do not meet the timeliness reporting.