PROBLEM TO BE SOLVED: To provide an odorant addition device which can drop an odorant stably into a gas supply pipe, independently of the magnitude of the flow rate of an object gas to be odorized flowing through the gas supply pipe.SOLUTION: An odorant addition device includes a dropping nozzle 2 which drops an odorant L into a gas supply pipe 1 through which an object gas G flows and an odorant supply path 3 supplying the odorant L to the dropping nozzle 2 and adjusts the dropping amount of the odorant L according to variation of the flow rate of the object gas. The dropping nozzle 2 has a storage part 4 which stores the odorant L supplied from the odorant supply path 3, a dropping opening 5 for dropping the odorant L into the gas supply pipe 1 and a narrow passage part 6 connecting the storage part 4 to the dropping opening 5. The storage part 4 is formed so as to decrease in cross section from an upper part 4a toward a lower part 4b, has a cross section equal to or smaller than the minimum cross section o
