Inmates were confined to their cells for hundreds of days over three months for breaking rules at Onley Prison, according to Ministry of Justice data.
The Howard League for Penal Reform say punishing inmates with confinement contributes to worsening conditions in prison.
Onley inmates committed 391 proven offences between July and September, of which 68 resulted in the culprit being confined to a cell.
The offending prisoners received 555 days of confinement - the equivalent of a year and a half between them.
HM Prison and Probation Service guidance states that adult prisoners can be confined to their cells for up to 21 days for a single offence, with young offenders getting up to 10 days.
Prisoners at Onley were most likely to be confined in their cells for non-violent offences, with 41 incidents over the three-month period.
Of these, 11 were for disobeying a direct order or breaking prison rules, for which the offenders spent a total of 77 days locked in their cells.
A further eight inmates received 70 days in confinement for possession of unauthorised items, from weapons to mobile phones.