Stock split is one kind of corporate action implemented by companies in order to rearrange stock price to be a more liquid range and provide more positive signal to investor. The higher liquidity of the shares stock the more attractive to investors. This research is aimed to analyze the difference between Bid-ask spread before and after stock split on the company listed in Indonesia Stock Exchange during 2009-2013. This research applies event study approach with 30 days observation which is divided into two, 15 days before and after stock split. This research applies descriptive and comparative method. The research sample are companies which perform stock split policy in 2009-2013 (24 companies) and using purposive sampling method. This research applies paired simple t-test as its data analysis technique using SPSS. The result shows that stock split causes bid-ask spread before and after stock split on the company listed in Indonesia Stock Exchange during 2009-2013.