Former Harford County Executive Charles B. Anderson Jr. broke into tears here tonight as he heard a jury's verdict acquitting him of all charges following a five-week political corruption trial.

The 48-year-old Anderson, a blunt-talking millionaire who left office in 1978, was hugged by codefendant Richard D. Schafer, a former county roads foreman, who also was acquitted and tearful.

After applauding the verdict from their seats in the Harford County Circuit courtroom, friends and well wishers rushed to greet the two men, and Anderson uncorked a bottle of champagne. Members of the jury smiled.

Anderson's trial was considered another turblent chapter in the stormy recent history of Maryland politics in which at least four local governments in the Baltimore area have come under investigation.

The charges in this case stemmed from the construction of a 70-foot section of dirt and asphalt driveway on property that Anderson had intended to purchase after leaving office.

Both the prosecution and the defense agreed that a special county roads crew under Schafer's supervision worked on the construction.

What was disputed in this largely rural county, where everyone knows everyone else and little extras often are considered a way of life, was how much of the work Anderson might legitimately have expected as a private citizen.

Lawyers Andrew Jay Graham, representing Schafer, and Peter Parker, appearing for Anderson, asserted that what was done on Anderson's driveway was "normal and commonplace."

According to testimony, the county will give away fill dirt on request and level asphalt on private driveways when a road is repaved.

"You get dirt, sure," argued Assistant State's Attorney Joseph Cassily, in rebuttal. "We've said that. Dirt is dirt. Do whatever you want with it. But don't shape it into a driveway."

Prospectors charged that substantial work was done at county expense and that the county should have been reimbursed.

Anderson, now a hardware and building supplies executive, said on the witness stant he was upset when he returned from a vacation in 1978 to see the newly laid asphalt on the driveway.

Although he knew the work would have caused no trouble for a private citizen, "I knew that because it was my driveway it was going to cause problems," he said.

Anderson's six-year administration was marked by bickering with the County Council, whose members consistently accused the close ally of former governor Marvin Mandel of favoritism in the award of county contracts and the conduct of county business.

His case had been seen as one of a series of investigations and trials that began in 1972 and during which executives of Baltimore and Anne Arundel counties were convicted of extortion and bribery.

Speaking last night of Anderson's trial in particular, his lawyer said prosecutors should "take a close second look" at this type of case before ruining a life on a case with what they called a weak factual basis.