PITTSBURGH (AP) _ The state Supreme Court on Friday suspended a semi-retired judge who dismissed rape charges against a man because the alleged victim was late for trial, then reinstated the charges five days later.

''Trial judges live with this all the time,'' said 77-year-old Allegheny County Judge J. Quint Salmon.''It's highly improper for any judge to comment on any matter still pending before the court. Therefore I have no comment.''

Prosecutors criticized Salmon after the charges were dismissed on March 20, and demonstrators protested his decision by picketing the courthouse and his home in neighboring Beaver County.

The Guardian Angels, an anti-crime organization of young civilians, began efforts toward impeaching Salmon, who, although retired, presides part-time in Allegheny County to help ease a backlog of cases.

Chief Justice Robert N.C. Nix Jr. ordered Salmon relieved of his judicial duties in Allegheny County ''after consultation with the full court,'' according to a statement issued by his Philadelphia office.

The state's highest-ranking judge also ordered an investigation of conduct by Salmon and Assistant District Attorney Lisa Vincler, who prosecuted the case.

Five days after his controversial ruling, Salmon declared he would consider the dismissal to be a mistrial, making Geoffrey Adams, 28, of Pittsburgh's Hill District, eligible for further prosecution.

Adams' court-appointed defense attorney, David Rothey, appealed the reversal, asking another judge to bar Salmon and the district attorney's office from further involvement in the case.

Rothey said the dismissal was the equivalent of an acquittal and that to resume prosecuting Adams would be unconstitutional double jeopardy. But he defended Salmon against critics who argued that he should be impeached.

''Judge Salmon is a respected member of the legal community,'' Rothey said. ''I think he's well-liked. He has rendered valuable service here in Pittsburgh. If there's an investigation of any kind, I think Judge Salmon will be vindicated.''

Salmon had dismissed the charges at Rothey's request because the 14-year- old girl who contends Adams raped and beat her in a car last August was 15 minutes to 30 minutes late appearing in court.

The girl and her mother said they were on a Port Authority Transit bus that was delayed in traffic.

In his appeal to another Allegheny County judge, Rothey argued that Mrs. Vincler was guilty of prosecutorial misconduct because she had other witnesses ready to testify and could have proceeded with the trial even though her star witness was not in court. When Mrs. Vincler failed to do so, the commonwealth forfeited its case against Adams, he said.

District Attorney Robert Colville said that pending appeals, Mrs. Vincler will remain on the case and the trial would be rescheduled.

He said Pennsylvania case law clearly states that dismissal of the rape charges can be overturned on appeals without exposing Adams to double jeopardy because the dismissal came at the request of the defense.

''Twenty minutes late does not seem to be a reason to throw the whole case out,'' Colville said by telephone. ''That's the basis of our position.''