The intercontinental ballistic missiles were in their "last stage" of development, Mr Kim announced during his New Year's message.
Pyongyang has conducted two nuclear tests in the past year, including its biggest one to date.
UN resolutions call for an end to North Korea's nuclear and missile tests.
Mr Kim, who took control of the secretive state following his father's death in 2011, said in a televised speech: "Research and development of cutting edge arms equipment is actively progressing and ICBM rocket test launch preparation is in its last stage."
