The armed man, wearing a ski mask, entered the hotel's reception area just before 3:30am. He threatened the lone man working at the front desk and bound his feet and hands.
The robber then got hold of the key to the hotel's night safe and raided it before fleeing.
The hotel's man on duty "eventually managed to free himself and hid in another room at the hotel before we were called," local sheriff Kåre Rykkje told news bureau NTB.
Police said they didn't know how much money had been taken. They refused to comment on whether the hotel managed to record the robbery on a security camera.
"We're now trying to get an overview of witnesses who may have seen or heard something," Rykkje said. "But it's difficult because the robbery occurred so early in the morning."
Fleischer's Hotel, situated between the Hardanger and Sogne fjords, is one of Norway's leading wooden hotels from the turn of the last century. The highly ornate hostelry, full of antiques, has housed royalty and a long list of celebrities over the years, including Kaiser Wilhelm of Germany, who was known for taking summer holidays in the Norwegian mountains and fjords.
