The collision-induced dissociation process, He(S-1(0))+HF(X(1)Sigma (+)(0))--> He(S-1(0))+H(S-2(1/2)) +F(P-2(3/2,1/2)), has been studied using a three-dimensional semiclassical coupled wave packet method with a focus on electronically nonadiabatic transitions induced by spin-orbit interaction. The radial motion is described by classical mechanics and the other degrees of freedom are treated quantum mechanically. The diabatic potential energy surfaces have been constructed with the diatomics-in-molecule approach. The diatomic potential energy curves for the ground and excited states are obtained from the ab initio electronic structure calculations at the multireference configuration interaction level. The calculated spin-orbit branching fraction depends only weakly on the initial vibrational quantum number of HF and on the total angular momentum. This implies that the branching fraction is determined mainly in the large-r(HF) regions where the spin-orbit interaction of the F atom is dominant. We also found that the electronic anisotropy interaction between the He atom and the F atom in HF plays a less important role in collision-induced dissociation processes.