The rockets, which are believed to be old Soviet-developed FROG rockets that DPRK has had since the 1960s, flew for 60 km (37 miles) before crashing into the sea, Yonhap said.
Six days ago, DPRK had fired 25 short-range rockets into the sea off its east coast.
ROK believes the short-range rocket launches conducted by DPRK this month are an "armed protest" against the ROK-U.S. military drills that are currently taking place. DPRK has denounced the joint military exercises as a preparation for war while Seoul and Washington have said the annual drills are defensive in nature.
Early last year, DPRK conducted its third nuclear weapons test, having successfully launched a long-range rocket in 2012 that critics say was aimed at proving technology for an intercontinental ballistic missile.
Both of those are banned under UN sanctions.