In a written answer to Parliament, education minister Stephen Twigg confirmed that five mistakes were made in January and two in the May and June papers.
The figure puts the board ahead of its rivals. OCR made two errors and AQA one this summer.
The Edexcel total does not include incidents where schools were warned of mistakes. For instance, the board said schools were told beforehand about an A-level business studies paper, where candidates were asked to answer all nine questions when there were 11.
George Turnbull, spokesman for the Joint Council for General Qualifications, said: "It is not an excuse but human errors have always been made. Fifty years ago there would be five questions on a single sheet of paper - and there were mistakes then. Now there are more exams and more papers with charts, graphs, illustrations and source material."
Bob Eden, deputy head of Colchester sixth-form college, where more than 2,000 students sat exams, said: "There have been one or two mistakes this summer but they have been fairly evenly spread among the boards. Frank Wingate, Edexcel head of external affairs, said: "A number of minor errors have been made out of thousands of papers. We are happy that the situation is getting better."
Errors have not been restricted to the English boards. The Welsh Joint Education Committee and the Northern Ireland board, the Council for the Curriculum, Examinations and Assessment, set two questions in A-level maths papers not covered by the syllabus.
* Two diagrams in an AS maths paper were incorrect.
* In a multiple-choice question in an economics A-level paper two of five possible answers were the same.
* Edexcel admitted errors were made in A-level English literature, A-level physics and health and social care GNVQ.
* Questions were missing from a communications key skills paper. Edexcel blamed the printers.
* Mistakes on two diagrams in GNVQ manufacturing and environment papers.
* In A-level business studies, candidates were asked to answer all nine questions when there were 11. Schools were warned before exam.
* AS-level history referred to "Steward" not "Stuart".
* AS biology exam faxed to the private Roedean girls' school 50 minutes late after the papers failed to arrive.
* Printing error in the AS-level government and politics paper left a table of figures with two columns transposed.
* Health studies GCSE contained incorrect information about microbes.
* Pupils faced questions on the medieval role of the church rather than Anglo-Saxon crime and punishment.
* Students who studied the poems of Robert Frost and RS Thomas found they were not in the anthology for the English literature GCSE exam.