An ink composition is provided that includes (a) an onium salt, a counteranion thereof having a volume of 1,000 .ANG..sup.3 or greater and (b) a cationically polymerizable compound. There is also provided an inkjet recording method that includes (a') a step of discharging the ink composition onto a recording medium and (b') a step of curing the ink composition by irradiating the discharged ink composition with actinic radiation. There are also provided a printed material obtained by the inkjet recording method, a process for producing a lithographic printing plate employing the ink composition, and a lithographic printing plate obtained by the production process.