The artwork, entitled Relative Value, was made up of 100,000 notes of 1,000 kroner (£83; 124 Euros) each, belonging to the artist, Jan Christensen.
The robbers got into the gallery by breaking a window.
They then cut each note off the canvas individually and left the 6.5-by-13ft (two-by-four-meter) frame behind.
The work had already been sold to a Norwegian buyer at face value.
“The piece was sold for nothing basically. It was just an exchange,” Mr Christensen told the BBC News website.
“I wanted to make a blunt work with the intention of creating a discussion about the value of art, and about capitalism, and how the art world works,” he said.
Mr Christensen said he did not know whether he would make a replacement.