There is provided an ultraviolet-curable ink jet composition, which is stored in an storage body, including a pigment; a pigment dispersant; a polymerizable compound; and a photopolymerization initiator, in which water content is 0.05 mass % to 1.0 mass % based on the total amount of the ultraviolet-curable ink jet composition, and in which both the acid value and the amine value of the pigment dispersant are 50 mgKOH/g or less, and at least one of the acid value and the amine value thereof is 10 mgKOH/g or more.