The present invention is intended to enable silver ions in an internal electrolyte solution of a reference electrode to be suppressed from being eluted, and also suppress a potential variation that occurs due to production of a poorly-soluble silver compound on surfaces of a liquid communication part and the like, and specifically provided with: an internal electrode formed of a silver/silver chlorides electrode; an internal electrolyte solution that is in contact with the internal electrode; and a containing body that contains the internal electrolyte solution, in which the containing body is formed of a material that does not have anionic conductivity but has cationic conductivity and moisture permeability.