Michael Donnellan noted that more than half of committals to prisons last year were fine defaulters.
New figures show that the number reached a peak in Cork Prison, where more than six out of 10 committals were fine-related.
The Courts Service recently announced that the new system of fine payment by installments, through local post offices, will come on stream by the end of the year.
For those who refuse to pay, there will be a separate system whereby judges can order the deduction of monies at source from a person’s wages.
“The impact of the new system will be huge,” Mr Donnellan told the Irish Examiner.
“Just think, last year there were more than 16,000 committals and more than half of them were fines. Can you imagine taking them out of the system?”
There were some 8,965 fine committals to prisons in 2014, representing 55% of the total (16,155). It marked the highest number of jailed fine defaulters on record. The number has more than trebled since 2008.
“They only come through the door and have to be processed to be left out again,” said Mr Donnellan.
The burden placed on jails in processing fine defaulters is greatest in Cork Prison.
Figures there show that, of the 2,654 committals in 2014, 1,672 (63%) were for the non-payment of fines.
This percentage has jumped over the years, accounting for just 24% of committals in 2008, reaching the 50% mark in 2011. It has continued to rise since then.
“In terms of committals, Cork is probably the biggest committal prison in the country, so processing all these people for fines is a huge drain on our resources,” said Mr Donnellan.
The Irish Prison Service director general was speaking to the Irish Examiner during a tour of the new €42m Cork Prison, which is expected to be operational by the end of the year. It will do away with the over-cramped conditions of the current prison and end the practice of slopping out, whereby inmates relieve themselves in a bucket which is then emptied the next morning.