Study about organic inhibitor has been performed to analyze effect of ginger extract concentration (Zingiber officinaler) to corrosion characteristic of API 5L grade steel under 3.5% NaCl and 0.1M HCl. Amount of 100 to 500 ppm inhibitor injected into each solution and electrochemistry tests were performed. Ginger extract has been prepared previously with maceration method and tested with FTIR to identify type compound in it. Tafel test result showed that corrosion rate of steel decreased in accordance with the increase of inhibitor's concentration. Corrosion rate decreased to 8.19 mpy at 500 ppm inhibitor under NaCl solution, with efficiency 54.79%. While in HCl, corrosion rate showed similar trend, with corrosion rate 12.14 mpy at 500 ppm, with efficiency 81.66%. EIS result showed that impedance increased with the increase of inhibitor's concentration, while FTIR result showed that ginger extract inhibitor contain 2- Methoxy-4-propylphenol which is known as antioxidant compound. According to XRD test, Fe2O3 and Fe3O4 compound were identified on steel surface. Ginger extract might worked better in acid environment since it decrease corrosion rate significantly compared to neutral solution.