Broadway impresario and theater owner James M. Nederlander has purchased the 42nd Street building housing the landmark New Amsterdam Theater--the legendary theater where Florenz Ziegfeld's "Follies" were staged--and in a multimillion-dollar effort, plans to restore it and another former theater on the property, according to Nederlander officials.

The purchase price could not belearned today.

In addition to the New Amsterdam Theater--which was converted into a movie house in the Depression year of 1933 and never again housed Broadway shows--the building also has an old 700-seat roof-garden theater.

The New Amsterdam is considered among the most ornate theaters in the world, and it and its rooftop companion were centerpieces of the famous Broadway boom of the 1920s. The two theaters were considered by many to represent the epitome of Manhattan society glamor and the Broadway style of show business' glory years.

An official for the Nederlander Organization, which operates the largest chain of live-attraction playhouses in the United States including 10 on Broadway, said today the firm would take possession of the building Thursday.

The New Amsterdam, on the street level of the building, now has its entrance on the raunchy, frequently dangerous movie theater row on 42nd Street. Nederlander intends to move the theater marquee and entrance way to the more sedate 41st Street.

When restored, the New Amsterdam is expected to have at least 1,700 seats and one of the largest stages on Broadway.

The first show to go into the theater, once it is reconverted to a legitimate playhouse, is to be "New Amsterdam Follies," modeled after the old "Ziegfeld Follies," according to the Nederlander Organization.

James M. Nederlander, in addition to having produced or coproduced more than 40 Broadway shows in the last decade, is the nation's leading private ballet impresario. Despite his predictions of substantial box office losses, he is importing superstar Rudolf Nureyev to star with the Boston Ballet in a sumptuous production of "Don Quixote," scheduled to open on Broadway in mid-January.