ABSTRAK :rnrnInvestors invest in capital market to get return. In order to get it, they must make investment decision (buy, hold, or sell stock) based on available information. One of the information that is available in capital market is earnings information. We can infer that earnings announcement has information content based on market reaction showed by significant abnormal return in the event period. Besides that, based on speed of market reaction to earnings announcement we can know if Indonesian capital market is efficient or not. This research also study how significant of earnings announcement to stock’s abnormal return. Finally, this research compare abnormal return between group of sample who announced increase in profit and group of sample who announced decrease in profit.