Theoretical expressions of time-resolved fluorescence were worked out in the system of intramolecular energy transfer where both donor and acceptor possess motional freedom of internal rotation. Forster-type mechanism was assumed for the intramolecular energy transfer. Effects of the internal rotations of the donor and acceptor on the fluorescence intensity and anisotropy decays were examined by numerical calculations for some model systems. It was suggested that anisotropy decay of the acceptor is very sensitive not only to molecular geometry of donor and acceptor, but also to the diffusion coefficient of the internal rotation of the donor.