Quiet, friendly, beautiful -- is this Northern Ireland?

Until the end of last year, Jim Gardner was a big shot at the De Lorean Motor Company automobile plant near Belfast. As head of labor relations, he had a well-appointed office, a company car, and a staff of 12. Then on Dec. 31 the De Lorean plant closed.

Mr. Gardner now drives a second-hand car, has no full-time secretary, and, for the first time in 38 years, receives no company paycheck at the end of the month.

But he is optimistic about his future. With the help of a British government grant and his own money and mortgaged assets, Mr. Gardner has opened a new company. Called Personnel Systems Ltd., it provides a consulting service for small- and medium-sized businesses.

After only five weeks in operation Mr. Gardner has secured several contracts. His enthusiasm typifies the feeling of many residents who have faith in Northern Ireland's future, despite years of violence.

Mr. Gardner was already thinking of starting his own company before De Lorean closed. He had planned eventually to move from the pressures of a large manufacturing plant, while continuing to work for De Lorean as an adviser. De Lorean's closure forced him to go it alone.

''The local enterprise development unit, a government agency, liked my plan and gave me some funding. However, I had to put all I have on the line and to back my judgment that the need for my consultancy does exist,'' he says.

The contracts have been coming in steadily, Gardner adds.

''I don't believe that Northern Ireland will become a financial desert. The synthetic fiber industry, which had a boom period in the '50s and '60s, is shrinking, and we are going through a transition. People here will have to be more constructive and create jobs which are based here, rather than [introducing ] new plants with outside bases. In hard times the branches over here are lopped off. We need to create our own trees.

''I know what I have to earn to stay afloat in 1983, but I am hoping to double that amount,'' he says. ''I don't want to leave Northern Ireland and I don't see why I should have to do so. There is a need right here, and I can supply it.''

This optimism is echoed by high school student Jenny Cleland, who wants to stay in Belfast to study to become a doctor. She received excellent grades in her examinations and could choose to enter one of several top medical schools in the United Kingdom. But she tops her list with Queen's University in Belfast, which has a world reputation for medical studies.

''The troubles here have not played a part in my decision. People of my generation are used to them,'' Jenny explains.

She has traveled a good deal, including a five-week trip to Milwaukee some time ago.

''I loved it,'' she says. ''People were good to me, and we had fun. But I was glad to come home. Northern Ireland is quieter and people tend to be more friendly with their neighbors.

''I also love the open-air life, and the countryside in Northern Ireland is beautiful. My roots are here, and I don't think that I would be happier anywhere else. I really do have faith in this place.''

Even non-natives are choosing to settle in Northern Ireland. American Eddie McIntire left Los Angeles with his Ulster-born wife three years ago to live in Ulster. The McIntires had spent their first vacation in Belfast.

''I liked it from the start,'' Mr. McIntire explains. ''People were more friendly and the pace of life was slower. It was only when we got back to California that we realized how difficult it was to adjust.''

The McIntires returned periodically on vacation and eventually decided to settle in Ulster with their three children. Eddie had to work hard to make a living and at one stage took three part-time jobs, but he has started a building business with a local man, and it has good prospects. He cites the advantages of Ulster schooling and health care, and he appreciates the intimacy and relaxed attitude of life in Northern Ireland.

''There's a lot to be said for this place, if people here would only pause and reflect on what they have. I've no intention of going back to California. In fact, my wife says I have settled in better than she has!''