RCMP Sgt. Alain LeBlanc said the man approached the guards at a Royal Bank branch in Lower Sackville on Thursday around 11:20 p.m.
LeBlanc said the suspect was wearing a Batman mask with a blue hooded sweat shirt, jeans and running shoes.
"It's certainly unusual," LeBlanc said. "Certainly I don't remember someone committing or attempting an armed robbery with a Batman mask."
LeBlanc said the man, believed to be in his 20s, fled the scene in a nearby minivan.
No one was hurt.
Police continue to search for a suspect.