The price of providing judges' accommodation in south Wales is criticised after figures showed it costs £417,000 annually.
Plaid Cymru's Freedom of Information request revealed the figures for lodgings in Cardiff and Swansea.
The party's, Chris Franks, said many would find it "totally unacceptable".
However, justice officials said the issue of lodgings is kept under review, "ensuring that tax payers' money is spent effectively".
But Plaid said there still remains a wide difference between the cost of judges' lodgings in south Wales compared to the accommodation bill for those attending courts in the Caernarfon area.
In Cardiff, the bill is £806 per night, while in Swansea the cost is £1,042 a night.
Her Majesty's Court Service (HMCS) own and maintain both the judges' properties in the cities, including employing at least five members of staff.
However, in Caernarfon, judges must use hotels rather than specific HMCS accommodation, at the cost of around £440 a night.
"Is there any justification for having premises in Cardiff and Swansea when hotel accommodation is used in Caernarfon?" asked Mr Franks.
"We can't afford to be housing judges in expensive premises when good quality alternatives are available. The annual running costs of lodgings in Cardiff are a staggering £239,000 and £178,000 in Swansea.
"Many people will find this spending totally unacceptable as they see their income at risk."
'Safe and secure'
Following the freedom of information requests that revealed the cost of judges accommodation in south Wales, Mr Franks has now called on HMCS to investigate cheaper options in Cardiff and Swansea.
Responding to the comments from Plaid Cymru, a spokesperson for the HMCS said: "The most serious and complex cases, both criminal and civil, are heard by High Court Judges in courts near to where the events took place and in a place most convenient to parties and witnesses.
"High Court Judges are based in London and need accommodation, often for long periods of time, when they hear cases outside London.
"HMCS keeps under review whether these lodgings effectively provide the High Court Judges with a safe, secure and suitable environment, giving them the privacy to work on cases and judgements while ensuring that taxpayers' money is spent effectively."