Abstract: A sealing composition which stops the leakage of a liquefied or compressed gas through a sliding contact section, includes 1 part of a hydrophilic organic polymer and 5-200 parts of a polyol. Usable hydrophilic organic polymers are synthetic and natural polymers including polysaccharides and their derivatives, which have average molecular weights of 10,000-10,000,000. Preferable is pullulan or elsinan which substantially consists of repeating maltotriose units. Any polyols are usable in the invention whether they are in non-crystalline or crystalline form, provided that they bear 2-20 carbon atoms and hydroxyl groups. The present composition may be further admixed with water and/or nonionic or anionic surface-active agent in an appropriate amount to facilitate the preparation of the composition and to regulate the viscosity of the composition.