The First Lady has been lambasted for her extravagance at a time when the economy is still struggling. One blogger went so far as to brand her a modern-day Marie Antoinette.
The exact cost of the trip is unclear as Mrs Obama, 46, and her friends are footing personal expenses – including accommodation at Marbella’s five-star Hotel Villa Padierna – themselves.
But the taxpayer will have to pick up the tab for the First Lady’s 68-strong security detail, her personal staff – and the use of presidential jet Air Force Two.
The cost of accommodating the secret service team runs at around £172 each a day which amounts to nearly £60,000 for the length of the summer break.
Use of Air Force Two, the Air Force version of a 757, comes in at £91,900 for the round trip. This does not include time on the ground.
The American public will also cover the cost of the only official part of the holiday, a visit to the Spanish royal family on the island of Majorca.
A conservative estimate puts the total amount at around £150,000.
Back in the U.S., anger was mounting – especially as it has emerged the First Lady will have enjoyed eight holidays by the end of the summer.
These include a trip to Los Angeles in June, a visit to the Florida’s oil-hit Gulf Coast next weekend and a ten-day trip to Martha’s Vineyard later this month.