Initial Public Offering according to 1995 Capital Market Law number 8 in the article 1 point 15 is defined as follow, "Initial Public Offering is an stock offering activity done by the issuer to sell the stock to the market in accordance with methods ruled by the law and the regulations" The parties involved in the initial public offering process are: 1. Underwriter 2. Public Accountant 3. Corporate Law Advisor 4. Underwriter Lawyer Due diligence is an absolute mandatory to the stakeholders to verify the accuracy of disclosure principle that is related with the securities company dan is a standard to investigate dan scrutinize which is a part of initial public offering preparation process that will be done by the company, so a few of parties interpret the due diligence with thorough investigation. The parties involved in the due diligence process are: 1. Underwriter 2. Corporate Law Advisor 3. Corporate Accountant While the due diligence process includes: 1. Legal Due Diligence 2. Financial Due Diligence 3. Business Due Diligence In this thesis, the writer used the initial public offering case study of the issuing of 2003 Mudharabah Shari a Bond of Bank Shari a Mandiri