And rather than prosecute the 44-year-old man, authorities decided to let him walk, leaving him to get help for his addiction on his own.
The man entered the Deutsche Bank on Monday morning, and initially queued up along with the other customers.
When he got to the bank teller, he handed over a note which read: "This is a robbery! I need money." He demanded €1,000.
But the man did not really want the money, and told the 23-year-old bank worker to press the alarm button.
They started chatting, and he admitted to her that he was actually seeking to be arrested so he could come off drugs.
The bank employee offered him a seat and a cup of coffee, while they waited for the police to arrive.
Other customers did not even realize they were involved in an on-going, would-be robbery, Frankfurt police said in a statement.
When officers got to the bank in central Frankfurt, they took the wannabe robber to the station, where he admitted everything, stressing he wanted to go to prison to get off drugs.
But he even failed to get this far.
"He didn't hurt anyone, didn't damage anything, so there was no reason for us to hold him. He was offered advice on where he could seek help for his addiction independently," a police spokesman told The Local, adding that it was not clear what drugs he had been taking.