The purpose of this study was to find out the practice earning management before merger and acquisitionannouncement. It also aimed to examine the differences of stock return before and after merger and acquisitionannouncement among companies that were listed on Indonesia stock exchange. The samples were 35 companiesthat did merger and acquisition and listed in Indonesia Stock Exchange (IDX) period 2004–2013. Then, thedata analysis was performed by computer statistic program SPSS. These samples were selected by usingpurposive sampling method. Analysis hypothesis used Independent sample t-test and Wilcoxon sign rankstest. The result of independent sample t-test showed that the companies tended to do earning managementbefore merger and acquisitions. While the result of Wilcoxon signed ranks test showed that there was nodifference between stock return before and after merger and acquisition announcement.