It is the first stage of a plan to make all jails in England and Wales smoke-free.
And from next month, smoking will be barred in the interior of all “open” prisons in England and Wales.
Earlier this year, the Prison Governors Association said a smoking ban risked making jails more unstable.
Its new president, Andrea Albutt, said tobacco could become an illicit currency.
A smoke-free policy will be implemented in all prisons in Wales – Cardiff, Parc, Swansea and Usk/Prescoed – from January 2016, and at four English prisons – Exeter, Channings Wood, Dartmoor and Erlestoke – from March 2016.