The present invention provides crystals of L-ornithine and a process for producing the crystals of L-ornithine including the steps of (i) exposing L-ornithine or a salt thereof, a composition comprising L-ornithine or a salt thereof, or a solution containing L-ornithine, a salt thereof, or the composition to a cation exchange resin to adsorb L-ornithine onto the cation exchange resin; (ii) eluting L-ornithine from the cation exchange resin on which L-ornithine is adsorbed with an aqueous alkaline solution, and removing an alkaline component from the resulting eluate to prepare an aqueous L-ornithine solution; and (iii) mixing the aqueous L-ornithine solution with a hydrophilic organic solvent, and crystallizing L-ornithine from the resulting mixed solution.