Duncan Fraser, who is in charge of history and vocational media at Edexcel, said the commercialisation of exams was reducing choice and leading to increased teaching to the test.
Controversially for someone from a board owned by Pearson, a major publisher of educational textbooks, he suggested the role of publishers in the exams system had had a damaging effect.
He told an Institute of Historical Research conference: "One effect is the syllabus becomes less a description of educational opportunities and more a contract with consequent effects on the way it is written and, of course, the way it is taught. Teaching to the syllabus, teaching for results, must narrow it and tend to depress the sense of inquiry and the desire to inquire."
He said commercialisation was a pressure facing all exam boards and had existed before Pearson took over Edexcel.
But the fact that he is a senior figure from the only one of three main exam boards run for profit will add weight to his comments.
He said the market was failing to bring the benefits its promoters had claimed and it was now more difficult for boards to offer minority subjects. "There is no blank cheque from government for running exams.
Running this whole process is very, very expensive," he said. "If not popular, an option can't be afforded: there is an element of truth in that."
The role of publishers, he said, increased pressure on exam boards. "Where there is no prospect of sales, books on a topic won't be published," he said. "If there are fewer resources, hard-pressed teachers won't take up those subjects so they become more difficult for us to award and more expensive for us to offer."
Ted Wragg, TES columnist and emeritus professor of education at Exeter university, said: "I would say 'Spot on, squire'. This is coming from the inside and it is absolutely right."
An Edexcel spokesman said competition between boards went back a long way, but teaching to the test was more an issue for the policy-makers and teachers than awarding bodies.
A spokeswoman for the Qualifications and Curriculum Authority said there was no evidence that commercial changes makes teaching to the test any more likely.