It is known that the diffuse H${alpha}$ halos around bright H II regions are more extended than the dust-scattered halos around point sources and the line ratios [S II] ${lambda}$6716/H${alpha}$ and [N II] ${lambda}$6583/H${alpha}$ observed outside of bright H II regions are generally higher than those in H II regions. These observational facts have been regarded as evidence against the dust-scattering origin of the diffuse H${alpha}$ emission and the effect of dust-scattering has been neglected in studying the diffuse H${alpha}$ emission. In this paper, we find, however, that dust-scattered halos of H II regions should be more extended than those of point sources and is in good agreement with the observed H${alpha}$ profiles around H II regions. We also found that the observed line ratios [S II]/H${alpha}$, [N II]/H${alpha}$, and He I ${lambda}$5876/H${alpha}$ in the diffuse regions can be well reproduced with the dust-scattered halos around H II regions which are photoionized by late O- and/or early B-type stars in the interstellar medium with the abundances close to those of the warm neutral medium. Therefore, we conclude that the diffuse H${alpha}$ emission may originate mostly from the dust-scattering.