The dielectric properties of a hydrogen-bonded side-chain liquid-crystalline polysiloxane have been examined over wide ranges of frequency and temperature. This polymer has a sidechain mesogenic moiety consisting of a benzoic acid and a stilbazole. The observed dielectric loss curves contain a component from dipole reorientation of the hydrogen-bonded mesogenic group. It has been found to be possible that, using electrical and thermal treatments, such a polymer built through hydrogen bonding can align homeotropically.