Ethephon not only has the effect in the stimulation of defoliation, but also makes fruits ripen quickly and evenly. Ethephon pushes hard the process of fruit ripening from 1-2 days instead of 4-6 days as before. However, the residues of Ethephon in the fruits will cause health problems such as damage to the liver, kidneys. The method used to determine Ethephon residues is high pressure liquid Chromatography Mass Spectrometry (LC-MS/MS). The limit of detection (LOD) Etherphon is 0.92 mg /kg and Limit of quantitation is LOQ = 2.7mg/Kg. The linear range curve is from 0.96ppm to 96ppm with R 2 = 0.999 repeatability. The study subjects are green bananas soaked in Ethephon solution with concentrations: 4.8%, 9.6%, and 24%. Soaking time was from 1 day, 2 days, 3 days, and 4 days. Results obtained after 4 days of experiments showed that Ethephon content in banana increased proportionally with the concentration of Ethephon in the solution. The highest increase was on day 1, measured at 90.5 ppm at soaked concentration 24%, and 42.2 ppm at 9.6% and finally is 21.9ppm at soaked concentration of Ethephon 4.8%. Till the second, third, and fourth day, Ethephon content in banana started to decrease. Ethephon content in bananas of the fourth day is 20ppm at soaked concentration 24%, 9.6ppm at soaked concentration 9.6% and 3.3 ppm at soaked concentration 4.8% of Ethephon solution tank. However, after 4 days, bananas soaked in Ethephon solution had blackened and become inedible in comparison with bananas soaked in the Etherphon solution only within 1 or 2 days, the banana still remained beautiful and edible.