NEWQUAY and St Austell MP Stephen Gilbert claimed £194,107 in expenses last year – more than any other Member of Parliament in Devon and Cornwall.
A large chunk of the cash – £134,500 – was spent on staff salaries, while £16,873 went on travel, £16,061 on accommodation and £22,177 on his constituency office.
Mr Gilbert, who employs his mother, Jackie Bull, as a £10,000 to £15,000-a-year "senior caseworker", has faced criticism over his expenses claims in the past.
But he said on Monday that the money was necessary to fund his travel between Cornwall and London, while staff were needed to deal with the 500 letters and e-mails he receives every week.
Details of MPs' expenses were revealed by the Independent Parliamentary Standards Authority (Ipsa) last week.
Mr Gilbert told the Cornish Guardian: "I don't think anyone would want a situation where only those with private wealth were able to stand for Parliament. These figures represent the cost of travelling between Cornwall and Westminster, staying in London during the week, maintaining an office in St Austell and for the salaries of the staff who support me.
"Since becoming an MP, I have always sought to balance the priorities of doing my job effectively, while also providing value for money for the taxpayer. I have recently reviewed my accommodation arrangements and staff structure to save further costs."
On the subject of employing his mother, he added: "Jackie is more than qualified for the job she does and was appointed through an independent interview process."
The Ipsa figures show Cornwall's six MPs cost taxpayers a total of £951,822 in 2012-13.
The second highest claimant in the county was Andrew George, who represents the St Ives constituency and received £174,150.
He was followed by Sarah Newton, of Truro and Falmouth, with £158,102; Sheryll Murray, of South East Cornwall, with £152,606; Dan Rogerson, of North Cornwall, with £140,312; and George Eustice, of Camborne and Redruth, with £132,545.
Mrs Murray said she did not claim for electricity or television in her London flat, adding: "I don't feel it's right for the taxpayer to pay. Whatever I claim I can 100 per cent justify. I don't think I've had one claim refused."
The total bill for all 650 MPs' expenses rose by more than 7 per cent last year to £98 million and spending is now higher than in the run-up to the scandal that rocked Westminster in 2009.
The publication comes in the wake of proposals to raise MPs' pay from £66,000 now to £74,000 after the 2015 general election – despite protests from David Cameron that the cost of politics must not be allowed to rise.
The TaxPayers' Alliance has said costs must be kept under control.