Even though not all activities were taken notice of, several were foiled, the head of the intelligence Hans-Georg Maassen confirmed.
He did not say what type of technology was procured, but said it could be used for civilian and military purposes.
Over the past year, the United Nations has repeatedly tightened sanctions on the reclusive state in response to leader Kim Jong-un's continued ballistic missile and nuclear tests.
A report submitted to the U.N. Security Council Friday said that North Korea had earned $200 million previous year in violation of sanctions and that China and Russian Federation hadn't stopped some exports from North Korea, according to the BBC.
NDR released portions of its interview with Maassen on Saturday, but the full program will be aired on Monday.
"When we see such things, we stop them. But we cannot guarantee that this can be detected and prevented by us in all cases".
Since 2008, photographer Eric Lafforgue ventured to North Korea six times.
It menacingly warned: "North Korea's nuclear weapons are a self-defensive deterrence not in contradiction of the worldwide law".
Pyongyang sold a ballistic missile system to Myanmar and may be helping Syria with a chemical weapons program, according to the report.
Relations between North Korea and the global community have continued to deteriorate over the past year after the country launched a series of intercontinental ballistic missile (ICBM) launches.
The continued tests have also sparked a war of words between US President Donald Trump and North Korean leader Kim Jong-un.
However, relations between Pyongyang and Seoul appear to have improved temporarily ahead of the Winter Olympics in Pyeongchang, South Korea.
North Korea has agreed to participate in the Games.