To provide a waterproof type light-emitting device mounted with an LED, and a method of assembling the same.SOLUTION: A repeater 100 which is a waterproof type light-emitting device comprises a substrate 1 having a through hole T, an enclosure 3 having a first enclosure wall 31 and housing the substrate 1, an LED 5 having a light-emitting part 50 arranged between the substrate 1 and enclosure 3 and having a light-emitting element and an LED pin 51 extending from the light-emitting part 50, a light guide seat part 6 guiding light of the light-emitting part 50 to outside the enclosure 3, and a sealing part 9 filling a region enclosed with the substrate 1 and enclosure 3 with resin. The first enclosure wall 31 has a seat part B mounted with the substrate 1 and a window part W where a window hole fitted with the light guide seat part 6 is formed. The LED 5 has the light-emitting part 50 supported by the light guide seat part 6, the substrate 1 is mounted on the seat part B with one end of the LED pin 51 inserted into the through hole T, and the light guide seat part 6 is held between the first enclosure wall 31 and substrate 1.SELECTED DRAWING: Figure 3