A rustproofing composition has superior properties satisfying rustproofing quality requirements and workability requirements for car underbodies, parts around tires, parts with pockets, plate-bonded parts or the like of car bodies, and containing volatile organic solvent of 20 mass % or less. In a rustproofing composition containing UV curable resin and photopolymerizing initiator and at least one of rustproofing oil and rustproofing wax, the content of nonvolatile component at 105° C. for 3 hours in the rustproofing oil and rustproofing wax is 80 mass % or more, the UV curable resin and photopolymerizing initiator are dissolved or dispersed in the rustproofing oil and rustproofing wax, and the UV curable resin is contained at 0.3 to 10 weight % to the total weight of the composition.