An ultraviolet hardenable ink composition excelling in the wetting characteristic (repellence prevention) of ink having impacted a recording medium. There is provided an ultraviolet hardenable ink composition characterized by containing a polyester-modified polydimethylsiloxane as a surfactant in an amount of 0.01 to 1% based on the ultraviolet hardenable ink. Preferably, at least allyl glycol and/or a N-vinyl compound is contained as a polymerizable compound. Incorporation of the polyester-modified polydimethylsiloxane in the surfactant has realized enhancing of the wetting characteristic on all nonabsorptive material surfaces and avoiding of ink repellence.