This study carried out an experiment to find out the reaction of hairtail, Trichinus lepturus to the colors of LED light as a basic study on the development of the trolling gear and a method to enable the day-night operation. We used hairtails caught around Seongsan-po, Jeju Island by set nets and hairtail angling. The seven hairtails of the average length 68.9 cm (SD 9.2 cm) and the average weight 135.9 g (SD 47.9 g) were adapted themselves in the experimental water tank, 15 m Self-Governing 1.7 m in height and 1.5 m in depth, and then they were studied. We conducted experiment at the Ocean and Fisheries Research Institute in Jeju Special Self-Governing Province, from November to December 2015, and the sea surface temperature was between 16.5 and 19.5℃. The four colors of LED light, blue, white, green and red, were set up to transmit downward from the marginal area of tank. The 1 meter depth light intensity of LED colors is as follows: 0.09 w/m2/s (blue), 0.18 w/m2/s (white), 0.04 w/m2/s (green) and 0.007 w/m2/s(red) To know the optimum LED color light, we selected one with better reaction rate after comparison of two colors simultaneously and the selected color was again compared to the other color in a tournament style two times a day (day and night) and ten times totally. The reaction rates were shown as the frequencies of hairtail appearance for 5 minutes in the lighting zone after turning on the LED lights. The reaction rate of the blue was at 97% unlike the red 3% (p < 0.001). The blue was at 75% unlike the green at 25% (p < 0.001). The blue was at 67% unlike the white at 33% (p < 0.001). Therefore, the color of light source showing the highest reaction rate was the blue.