The test was conducted under leader Kim Jong-un’s supervision, North Korea's state news agency reported on Thursday.
Kim "noted with great pleasure that the successful test... helped boost the power of ballistic rockets capable of mercilessly striking hostile forces," KCNA said.
Solid-fuel rockets have advantages in military use, although liquid-fuel rockets are considered more sophisticated because of their controllable thrust.
The alleged test follows Pyongyang’s simulated test of an atmospheric re-entry of a ballistic missile last week that accelerated the country’s push to produce ballistic missiles capable of carrying nuclear warheads.
Pyongyang is in possession of short and medium-range missiles but has yet to build solid-fuel long-range or intercontinental ballistic missiles.
The tests were conducted in defiance of sanctions by the UN Security Council that ban North Korea from carrying out all ballistic missile activities.
Following the North's fourth nuclear test in January and an alleged satellite launch the next month, the US and China formed a front in the UN to slap new sanctions on Pyongyang.
Earlier this month, the Security Council imposed its “toughest” sanctions on North Korea, targeting the country’s military, mining, trade and financial sectors.
But the North responded by firing a number of rockets into the waters off its eastern coast on several occasions.
Pyongyang also stepped up its anti-US rhetoric over the past few weeks, threatening Washington of pre-emptive nuclear strikes.
The country bills its nuclear and missile programs as deterrence against plots by the US and its allies to overthrow the regime in Pyongyang, Press TV reported.
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