Bid-Ask Spread is one of the most common variables used by the investor to decide where to invest in a company. By analyzing Bid-Ask Spread and the factors influencing it, the investor is expected to be able to maximize profit and minimize loss. The purpose of this research is to analyze the influence of financial leverage and stock trading volume activity toward Bid-Ask Spread. This research uses purposive sampling method in collecting data. Data were taken from 33 companies listed L-Q45 registered in Indonesian stock exchange (IDX) from 2011 – 2012. This research used multiple regression analysis to examine the effect of stock price, stock trading volume, and variance return on bid-ask spread. This research also used t test (partial test) and F test (simultaneous test) for the hypothesis testing. The result shows that financial leverage has positive influence toward bid-ask spread. Stock trading volume activity has negative influence on bid-ask spread. F-test shows that financial leverage and stock trading volume activity simultaneously has significant effect toward bid-ask spread. Keywords: Bid-Ask Spread, Financial Leverage, Trading volume activity. ABSTRAK Bid-Ask Spreadadalahsalahsatuvariabel yang seringdigunakanolehpara investor dalammenentukanperusahaanuntukberinvestasi.DenganmenganalisaBid-Ask Spreaddanfaktor-faktor yang mempengaruhinya, investor diharapkanbisamemaksimalkankeuntungandanmenimimalisirkerugian.Tujuanpenelitianiniadalahuntukmenganalisapengaruhfinancial leveragedanvolume perdagangansahamterhadapBid-Ask Spread. Penelitianinimenggunakanmetodepurposive samplingdalammengumpulkan data.Data diambildari 33 perusahaan yang terdaftar di Indonesian Stock Exchange (IDX) yang tergabungkedalam L-Q45 selamaperiode 2011-2012.Penelitianinimenggunakananalisis linear bergandadalammenentukanpengaruhfinancial leveragedanaktivitasperdagangansahamterhadapBid-Ask Spread.PenelitianinimenggunakanUjiparsial (Uji t) danUjiSimultan (Uji F) dalampengujianhipotesis. Hasilpenelitianmenunjukkanbahwafinancial leveragememilikipengaruh negative terhadapBid-Ask Spread.Volume perdagangansahammemilikipengaruhpositifterhadapBid-Ask Spread.Ujisimultanmenunjukkanbahwafinancial leveragedan volume perdagangansahamsecarabersama-samaberpengaruhsignifikanterhadapBid-Ask Spread. Keywords: Bid-Ask Spread, Financial Leverage, Volume perdagangansaham.