Development of the missile was revealed Monday by the Joint Chiefs of Staff at a meeting attended by the legislator, Yonhap News Agency reported.
The missile has a range of 62 miles. It was successfully test fired in May, the South Korean lawmaker said, and is designed to be launched from a multiple launch rocket system.
It uses a ground-based navigation system resistant to jamming signals, he added.
Another committee member reported the military officers said the missile's ability to penetrate bunkers and locate tunnel entrances has been completed.
President Lee Myung-bak ordered the project after North Korea shelled the island of Yeonpyeong in November 2010, killing four South Koreans.
Pyongyang failed in an attempt to launch a rocket in April that was widely seen as a long-range missile test.