They had earlier been investigated and charged by the department. They were sacked as part of the disciplinary action accompanying the charges.
Vitaya Suriyawong, director-general of the department, said on Tuesday that the 14 sacked officials were at specialised and operational levels. Three of them were arrested for possessing drugs, 10 smuggled drugs and mobile phones into prisons, and one was absent from work for more than 15 days without leave.
The director-general also said that inmates guilty of serious crimes would be moved to eight maximum security prisons and their warders would be carefully selected.
Warders, especially those at maximum security prisons, would receive better pay to encourage their honesty, and corrupt staff would be sacked, Mr Vitaya said.
The expulsions sent a message that the department was taking serious action against officials involved with illicit drugs, he said.
His department is seeking an additional 1.2 billion baht from the government to pay increased overtime and position allowances for warders and to recruit 1,183 new warders for maximum security prisons.
Mr Vitaya said Justice Minister Gen Paiboon Khumchaya had already approved the budget request.