Credit institutions are not allowed to use them while supplying services to customers.
The ownership and trading of bitcoin and similar currencies poses many risks as they are not protected by the law.
The bank warned organisations and individuals not to invest or conduct any payment with them.
First appearing on the Japan-based Mt.Gox exchange in June 2010, bitcoin has been widely used since early 2013 for payment and investment.
Many governments, including Thailand, Russia, France, China and Norway, do not recognise it as a legal currency.