Ronald Prescott Reagan, the younger son of President Reagan, has told some of his friends he plans to end his career as a ballet dancer next week, the friends said today.

Reagan, a member of the Joffrey Ballet since last autumn, has been dancing secondary roles as a member of the company in Manhattan for the last four weeks. He had been in the Joffrey's junior company, the Joffrey II, for two years before that.

Dancer Reagan today refused to comment on whether he is giving up ballet. "Well, that may be. You'll just have to wait and see. I'm not going to talk to you about my plans for the future, whatever they may be, at this time," he said.

"If it's true, then you'll find out sooner or later. And if it's not, you'll find that out. too, and then we'll all know."

He said he was not denying the possibility, "and I haven't confirmed it, either."

The Joffrey company is scheduled to end its Manhattan engagement Sunday night and the dancers are to be furloughed until Feb. 7, when they begin rehearsals for the company's Kennedy Center performances--set for Feb. 22 through 27.

Further layoffs of the dancers are scheduled this year. One of Reagan's friends today said Reagan had said he could not again face the embarrassment of the unemployment line.

Late last year, with the Joffrey in continued financial turmoil, Reagan and the company's other dancers qualified for and accepted unemployment insurance. Pictures of the president's son on the unemployment line appeared in newspapers throughout the world.

Anthony A. Bliss, chairman of the board of the Joffrey, when asked if Reagan was giving up his ballet career, said he was unaware of the dancer's plans.

"I would not be surprised with any dancer who starts a career as late" as did Reagan, "looking down the road . . . and wondering if he wants to devote his life to that sort of schedule," Bliss said.

Veteran observers who have seen Reagan dance say he has stage charisma but lacks the technical capability to become a star dancer.