Nancy Reagan's chief of staff says the first lady's new director of projects, Kenneth L. Barun, is being hired at a salary of $60,000 a year, $15,000 more than his predecessor in the job, because he has "outstanding qualifications" and not because he is a man.

"He has four mouths to feed, which doesn't make any difference, a woman could have that, so I'm not saying that . . . Whether it's a man or woman has nothing to do with it," James S. Rosebush said of Barun, a former drug addict from Houston, who will direct Mrs. Reagan's crusade against drug abuse as well as her other projects.

"I'm saying his experience qualified him for that. Otherwise, we couldn't have gotten him, and he is going to bring so much credibility to Mrs. Reagan's drug program," Rosebush said. "He's already told her what it's like to be on cocaine. Well, I'm sorry. I was never on cocaine. I can't tell her that, and neither can departing projects director Ann Wrobleski."

Rosebush said the job description for projects director is unchanged, but that he felt Barun's qualifications and background were "so superior" that "we got the salary moved up to get him . . . He already took a cut to come here.

Rosebush said Barun's salary, which is also about $5,000 more than those paid social secretary Gahl Hodges or press secretary Jennefer Hirshberg, has not created any dissension among Mrs. Reagan's East Wing staffers.

But the first lady's chief of staff said it does "burn me up for a person to come in and say I hired him Barun at more money. It's just sort of the implication. It could have been a man, a woman, a chimpanzee. The reason he was hired at $60,000 is because he's run the second largest drug program in the country, Cenikor."

Barun was making $100,000 a year at the drug and alcohol rehabilitation program known as Cenikor Foundation Inc., according to Rosebush, when he resigned his Houston post to accept a $72,000-a-year job at the Department of Health and Human Services as deputy assistant secretary for public affairs. Last fall, Barun worked as a volunteer in the Reagan/Bush campaign. Three weeks ago he moved to Washington and HHS.

Hirshberg, who was named last week to succeed Sheila Tate as Mrs. Reagan's press secretary at a salary of $53,733, took a $12,000-a-year cut from what she earned as director of the Federal Trade Commission's Office of Public Affairs.

Rosebush also announced last week that Barun had been hired to succeed Wrobleski, who is moving over to a $60,000-a-year job at the State Department as deputy assistant secretary of state for international narcotics matters. Wrobleski's White House salary had been stalled at about $45,000.

"She did a wonderful job and I fought to get her more money, I most certainly did. I fought for three solid years," said Rosebush.

A spokesman in the White House office of personnel said Barun's salary is an "administrative determination of the people doing the hiring. Ultimately, that determination probably rested with Rosebush, Donald Regan and Mrs. Reagan."