The 20-year-old made his break for freedom on Sunday, crossing over two fences and becoming entangled in barbed wire, before pulling himself loose and hiding in a nearby forest.
There he was tracked down by a police sniffer dog after spending two and a half hours on the loose.
Prison Director Knut Bjarkeid told VG newspaper on Sunday that his staff were studying video camera footage to understand how the man, who was convicted on drugs offences, had escaped.
"Experience shows that situations like this arise when both technical systems and people fail," he said.
The Norwegian prison service last year constructed a special facility for Anders Breivik at Ila, where the far-right terrorist is expected to spend most of his 21-year sentence.
However, at the start of August, the killer was moved temporarily to Skien prison, south of Oslo.