NEW YORK (AP) _ Jane Amsterdam, founding editor of Manhattan,inc. magazine, will be named editor of the New York Post, a spokesman for the Post said Monday.

Howard J. Rubenstein, the spokesman, said the Post will make an announcement Tuesday naming Ms. Amsterdam, 36, to the position. She will start work in about a month, he said.

She will replace Frank Devine, who is expected to leave by the end of the year, Rubenstein said.

Devine stayed on after Rupert Murdoch sold the paper in March to Peter S. Kalikow, the real-estate developer, who made Peter O. Price publisher.

Ms. Amsterdam was an editor in the Style section and the investigative unit of The Washington Post, and executive editor at New Times, American Lawyer and New York magazines.

She is generally credited with making a success of Manhattan,inc., which was founded in 1984 as an upscale city magazine that treated top business executives as celebrities.

She resigned in March 1987 after a disagreement over editorial autonomy with the owner of the magazine, D. Herbert Lipson. In January, she joined Knopf as a senior editor.

According to the American Society of Newspaper Editors, Ms. Amsterdam would become the sixth woman currently holding the position of top editor at a newspaper with a circulation of more than 100,000.

The Post is the nation's oldest continually published daily newspaper.