The five, aged 23-37, are Pham Van Tuan, Pham Van Luan, Nguyen Van Mui, Dang Van Linh and Vu Dinh Duong.
The police are hunting for Nguyen Van Nam, 34, the alleged mastermind in the kidnap of the businessman, 43, identified only as T, on July 12.
The five said T was Nam’s business partner and had verbally guaranteed the loan.
But after the friend fled without paying, Nam kidnapped T.
Investigators said Nam asked T, who is based in Ho Chi Minh City, to fly to Hanoi where he had the men kidnap him.
They threatened to cut his hands and legs off if he failed to get back the money.
T phoned a friend, who has not been identified, and asked him for the money. But his friend reported to the Chinese embassy in Hanoi, which reported to the Ministry of Public Security.
The police rescued T and arrested the five men at a hotel in Bac Ninh Province on July 14.
The investigations are continuing.