  The near-threshold exotic hadrons such as $T_{cc}$ and $X(3872)$ are naively
considered as the hadronic molecular state from the viewpoint of the low-energy
universality. However, it is also known that the elementary dominant state is
not completely excluded as the internal structure of the near-threshold states.
Furthermore, the dominance of molecules is expected to be modified by the decay
or coupled channels. We discuss these features of the near-threshold bound
states by calculating the compositeness with the effective field theory.
