  On the basis of the Gerlach-Sengupta theory of gauge-invariant perturbations,
a formula of the integrated Sachs-Wolfe effect for a central observer is
derived on general spherically symmetric spacetimes. It will be useful for
comparative studies of theoretical and observational aspects of the integrated
Sachs-Wolfe effect in the Lemaitre-Tolman-Bondi cosmological models which have
been noticed by explaining the apparent acceleration without cosmological
constant.
