  The compositeness is defined as the weight of the hadronic molecule in the
hadron wave function. We can determine the internal structure of the
weak-binding system without any specific models from the compositeness. In
order to estimate the compositeness of the system with a large effective range,
we introduce the range correction to Weinberg's weak-binding relation by
modifying the correction terms. We study the applicability of the weak-binding
relations by the numerical calculation and show that the improved relation can
be applied to a larger parameter region compared with the previous one.
