Common Cause, seeking to build support for legislation further restricting campaign contributions by political action committees, yesterday released a report showing that the average amount of PAC money going to senators has increased by 53 percent in two years.

From the start of 1985 through June 30 of this year, PACs donated $24.2 million to the 87 candidates currently running for the Senate, according to the study. By June 30, 1984, PACs had given $14.6 million to 73 Senate candidates.

For incumbents running this year, the average amount of PAC receipts is $562,099, compared with an average of $367,306 for 1984 incumbents, the group found. Incumbents raise far more money than challengers from PACs; incumbents get $4.60 for ever $1 donated to challengers.

Common Cause president Fred Wertheimer contended that "PACs are running wild in the Congress. Senators are not controlling the PAC system, the PAC system is controlling them."

Wertheimer is pressing for Senate passage of legislation sponsored by Sen. David L. Boren (D-Okla.) that would restrict the amount of PAC money House and Senate members could receive and would lower the maximum PAC contribution from $5,000 to $3,000. The legislation is scheduled for a Senate vote next month.

The leading PAC recipients, according to the study, are Sen. Bob Packwood (R-Ore.), chairman of the tax-writing Finance Committee and a key author of pending tax-revision legislation, with $997,817; Sen. Steve Symms (R-Idaho), a member of Finance Committee, $870,561; Minority Whip Alan Cranston (D-Calif.), $869,849, and Majority Leader Robert J. Dole (R-Kan.), $815,904.

In addition, the study found that 11 Senate candidates, including seven incumbents, reported having more than $1 million in the bank as of June 30.

Sen. Alfonse M. D'Amato (R-N.Y.) has the largest balance, $3.2 million, followed by Packwood, $2.2 million; Dole, $2.1 million; Sen. Don Nickles (R-Okla.), $1.9 million; Sen. Arlen Specter (R-Pa.), $1.7 million; Florida Gov. Bob Graham (D), $1.6 million; Cranston, $1.4 million; Missouri Gov. Christopher S. Bond (R), $1.4 million; Sen. Charles E. Grassley (R-Iowa), $1.3 million; Sen. Robert W. Kasten Jr. (R-Wis.), $1.2 million, and Rep. W. Henson Moore (R-La.), $1.1 million.