The figures also show the number of investment companies which charge less than one per cent for their services has fallen compared to a year ago.
The research revealed that 30 per cent of the 251 investment companies polled charged less than one per cent for the year, down on 34 per cent from the previous year's data.
"The increasing charges reflect the improving performances of the trusts. Many of them hit their performance targets as the economy moved into recovery, which means their total expense ratios (TERs) went up, and their charges with it," Simon Elliott, analyst at WINS Research explained.
He added that, while specialist funds do charge more, it is because they offer a specialist service, and investors should not necessarily avoid them because of the cost.
Meanwhile, 58 per cent of investment companies have charges this year of less than 1.5 per cent.
The Global Growth sector lead the herd this year, with 60 per cent of its companies charging less than one per cent. UK Growth and Income followed, and the Global Growth & Income sector came third.
The Edinburgh US Tracker Trust charges investors the least, with a TER of 0.38 per cent. The City of London Investment Trust, Independent Investment Trust and HGCapital Trust all have low charges as well, the data showed.
Performance of investment trusts over 1-yr
Source: Financial Express Analytics
"The retail orientated investment company sectors continue, on average, to offer investors excellent value for money. Whilst charges are only one of several factors to bear in mind, they are an important consideration," said Ian Sayers, director general of the AIC.