Ichiro Ozawa, the veteran Japanese lawmaker who engineered the ruling party’s rise to power, was acquitted Thursday in a political funding scandal that has damaged his chances of becoming prime minister.

The scandal also cost Ozawa his membership in the ruling Democratic Party of Japan, though he continued to wield great influence as a political power broker. The acquittal means his membership could be reinstated, allowing him to exert even more sway.

The 69-year-old was charged last year with overseeing false accounting by his former aides in a murky 2004 land deal. Prosecutors claimed the three aides, who were convicted last year and have since appealed, acted under Ozawa’s orders, but the Tokyo District Court said it found no evidence of that.

Though Ozawa played a key role in the party’s historic rise to power in 2009, defeating the long-ruling conservatives, he is unpopular with voters and has a negative image as an old-style, wheeling and dealing “shadow shogun.’’ He still has a loyal core of supporters, many of them young politicians whose careers he helped launch.

Prosecutors alleged Ozawa was fully aware of false bookkeeping by the three aides to cover up questionable funds used in the land deal, and that he authorized the false entry of the transaction in an annual political funds report to the government.

Ozawa repeatedly told the court he had no knowledge of his aides’ actions. He said his indictment was based on an “unjust and illegal’’ investigation and demanded that the trial be scrapped.

The three aides, who were tried as a group, were given suspended prison terms of up to three years for failing to register a 400 million yen ($5 million) loan from Ozawa to his funding body in the Tokyo land deal and for accepting 100 million yen ($1.3 million) in illegal donations from a construction company.