PROBLEM TO BE SOLVED: To enable easy fitting of a transmitter to a water bird as one aspect.SOLUTION: A transmitter fitting device 10 has a transmission unit 12, a cord 14 and a connection member 16. The transmission unit 12 has a collar 18 that floats on water in an annular shape and is fitted to the neck of a water bird, and a transmitter 20 attached to the collar 18. One end of the cord 14 is fixed to a fixation object 32 and the other end of the cord 14 is connected to the transmission unit 12 via the connection member 16. The connection member 16 has lower tensile strength than the cord 14.
