The Rev. Benjamin F. Chavis Jr., the NAACP's executive director, said yesterday that the O. J. Simpson murder case "makes my job harder" because it is likely to harden the negative stereotypes that some Americans hold about black men.

Dr. Chavis told editorial writers at The Sun yesterday that he hadn't commented before on the Simpson case because he believed that it was not "a matter of racial justice" but the tragic fall of an "American hero." He said: "What I would caution against is people taking O. J.'s experience and extrapolating it [to cover] all African-American males. That would be a greater tragedy."