The director of the Bureau of Engraving and Printing, which is the subject of Justice Department and congressional conflict-of-interest investigations, has announced his retirement.

Seymour Berry, 56, is one of about half a dozen top bureau officials to leave over the past 18 months, according to Treasury Department sources.

In a letter to Treasury Secretary W. Michael Blumenthal, Berry said he was retiring after 37 years with the bureau to accept private employment. A department spokesman said he did not know whether Berry's retirement was related to the investigations. "He retired entirely on his own initiative," the spokesman said.

Berry relayed word through his secretary that he would not answer questions about his decision.

The investigations focus in part on Berry's predecessor, former bureau director James A. Conlon. Conlon resigned in June 1977 and immediately accepted a high-level job with the bureau's largest printing contractor, American Bank Note Co.

Conlon first received an "informal offer" from American Bank Note about a year before he actually retired, according to a company spokesman. Between that offer and Conlon's retirement, Treasury Department records show that American Bank Note received $16 million in new bureau contracts on top of the millions it has always received as one of the two major domestic contractors for the bureau.

Federal law bars an official from negotiating contracts with a company with which the official has any understanding concerning future employment.

American Bank Note installed Conlon as the first president of a subsidiary -- American Bank Note Development Co. -- based in Crystal City, Va. That subsidiary, responsible for soliciting business from foreign customers, had not operated prior to Conlon's arrival, though it had been formed about four months earlier, American Bank Note officials said. Conlon brought with him his top bureau deputy, Richard Sennett.

Both Conlon and company officials have denied any wrongdoing.

The Senate permanent investigations subcommittee began its inquiry after receiving critical audits of the bureau from the General Accounting Office.

The GAO reported that American Bank Note "may have realized profits substantially in excess of profits called for in its contracts" with the bureau for the printing of food stamps.

"Until September 1977," the subcommittee staff reported, "the bureau failed to perform" proper audits of the contracts. When it finally did, the audits "reflected unusually high profits under certain negotiated contracts."

"Bureau management did not move effectively to protect the government's interest," the staff said in a letter last month to Sen. Abraham Ribicoff (D-Conn.), chairman of the Senate Government Operations Committee.

The Treasury Department launched its own investigation as well, ultimately referring its findings to the Justice Department for a possible criminal investigation.

The department also temporarily transferred all of the bureau's contract awarding authority directly into Blumenthal's office pending the outcome of the probes.

Am American Bank Note Co. source said that the company had "always had an interest" in hiring Conlon, partly because of his 35 years of experience and his contacts with foreign government engraving and printing operations.

American Bank Note is one of the few firms around the world specializing in printing food stamps and other legal certificates.

Berry, in his letter of resignation, said his retirement would take effect on April 7. He said he will then pursue a career as a labor arbitrator.