The president of George Mason University, Northern Virginia's only four-year university, resigned yesterday from his $37,000-a-year post after four years in office, explaining later he "wanted a change."

Dr. Vergil H. Dykstra, who sent a memo to the school's faculty only one month ago denying rumors that he was about to resign, said yesterday that "to go into all the factors which went into my decision would lead to a very complex discussion."

Dykstra said he asked for a three-month leave of absence because he "needed a rest" and that since "I didn't feel I wanted to come back at the end of my vacation, I thought it only fair to tell the Board of Visitors at this time."

Dyskstra began his vacation yesterday and his resignation will become effective June 30. Dr. Robert C. Krug, currently vice president for academic affairs, has been appointed action president.

The rector of the university's 16 member Board of Visitors, John. T. Hazel, who said he was surprised when told of Dydstra's decision last week, announced that a search committee will be set up within two weeks to seek out candidates to fill the post.

Hazel, who said Dykstra had made "an outstanding contribution" to the university, dismissed the idea that the college president left his post because of complaints that the state legislature was not giving enough funding to the Northern Virginia school.

An $86 million construction bond approved by the General Assembly in its recent session grants only $6 million to George Mason.

Dykstra said he has been "disappointed in the lack of support for the school from the state in both salaries and in building construction" but that his was not a reason for his departure.

The lowa-born administrator is the second president of George Mason since it became a four-year university in 1972 and he has presided over a period of rapid growth.

In 1972 there were only 2,500 students at the school. This year's enrollment is more thant 8,700 including 4,500 full-time students.