Lord Armstrong of Ilminster, chairman of the trustees, said the decision was taken with "some reluctance" after investigating a series of options - including closing the entire museum for up to three days a week, or closing one of its branchescompletely.
It is another erosion of the principle of free museum entry, but will make little effective difference at the V&A, as it already charges "voluntary" donations of pounds 4.50 a head, which only the most brazen have the nerve to refuse to pay.
The blow will be cushioned by concessions for the elderly and for students, and free entry for under-18s. The museum will continue to allow free entry from 4.30pm to 6pm daily.
The move has been triggered by the V&A's parlous financial state. Its pounds 30m grant-in-aid was cut by pounds 1m this year and will be cut by the same amount next year. The museum has to find up to pounds 100m for repairs by the year 2000.
Paradoxically, it also announced yesterday that it had decided to build a pounds 43m "iconic" building in the middle of its South Kensington site, hopefully funded by the National Lottery.
The building is to be designed by Daniel Libeskind, the Polish architect of the Jewish Museum, Berlin, which famously looks like a bolt of lightning, and Bremen Philharmonic Hall. The new space - models of which show a bizarre series of slabs which appear to explode outwards - will house a restaurant, an observation point, a cafe and a major exhibition space. "There is a paradox here, and if you ask me if I think it is sensible, my answer is no," Dr Alan Borg, the V&A's director, admitted. "But there is nothing we can do. It would be entirely foolish of us to say we don't want to build grand projects just because the Government grant has been cut."
Dr Borg is known to be more in favour of admission charges than many of his colleagues, and introduced a similar system at the Imperial War Museum. He argues that it is preferable to charge than let standards fall.
His decision will come as no surprise to the museum world. In November he warned that the V&A had many galleries in a disgraceful condition and said that few of the 144 were in an adequate state of repair.
Mandatory charging will also end the present uncomfortable situation where visitors are "asked" to pay as they file in. "A lot of people are deeply irritated by this sort of charging. It makes them feel guilty and puts them on the spot in a way normal charges don't," said Robin Cole-Hamilton, head of public services.
The museum is unsure of the extent to which charges will affect visitor numbers, although when voluntary charges were introduced in 1985, visitors plummeted from 1.7 million to 1 million. Staff estimate, however, a drop of 20 to 30 per cent. That could mean the loss of 460,000 visitors from its present level of 1.4 million a year, but still raise income from its present pounds 1m to more than pounds 2.5m.
Meanwhile the "Boilerhouse" building by Libeskind should unlock efficiencies throughout the site, allowing better use of space and increased income. Dr Borg denied that the V&A, unable to foot present running costs, would be adding to them as a result of the new building. "It is absolutely essential to move forward," he said.