''It was not the Justice Department that ruled him out,'' Mr. Meese told reporters after a speech here this evening to a conservative law group. ''I think he withdrew because he saw this was going to be a long drawn-out thing and he did not want to embarrass the Administration. The President was prepared to back him fully and so was I.'' Mr. Meese said that he expected the President to select a new nominee ''within the next week or so'' and that he hoped the Senate Judiciary Committee would keep to the confirmation hearing schedule that had been established for Judge Ginsburg. Under that schedule hearings would begin on Dec. 7.

Judge Ginsburg chose to read his statement of withdrawal in person at the White House today. The 41-year-old judge and former law professor entered the White House press room this afternoon wearing a dark blue three-piece suit, and read from a hand-written statement on a piece of yellow legal-sized paper.

After noting the attention that had been focused on his personal life, he praised the President and his wife, Nancy, for their work on drug abuse, and expressed the hope that young Americans, ''including my own daughters, will learn from my mistake'' and listen to the Reagans' advice. A Tumultuous Week

His statement climaxed a tumultuous week that seemed to bring a new disclosure about the judge almost daily. One White House strategist said that the hasty announcement today was motivated in part out of concern that newspapers would publish another wave of disclosures Sunday.

The growing unhappiness among the judge's supporters surfaced publicly Friday, when William J. Bennett, the Secretary of Education, called him to urge his withdrawal. The Secretary, according to his aides, told Judge Ginsburg that his cause was ''no longer winnable, and was very damaging to the Administration.''

That view was widely shared inside the Administration and among its supporters on Capitol Hill. Twenty to 30 senators concluded that the judge could not be confirmed, and their views, communicated to Judge Ginsburg by Administration officials, had a major effect on his decision, according to a senior official.

Another important voice was that of William Bradford Reynolds, the Assistant Attorney General for Civil Rights, who was a major force in persuading the President to select Judge Ginsburg. Mr. Reynolds spoke to the judge Friday night, officials said, and told him that his situation was desperate. Engineering the Decision