Timothy Rub, the director and chief executive officer of the Philadelphia Museum of Art, on Wednesday apologized to hundreds of employees, saying the institution had made mistakes in the way it dealt with a former manager several female staff members have accused of sexual harassment.

Mr. Rub’s remarks, made at a closed-door, all-staff morning meeting before the museum opened to the public, addressed the allegations that have surfaced against Joshua Helmer, the former assistant director for interpretation at the museum. In 2018, he left and went on to become director of the art museum in Erie, Pa., where an intern made a similar complaint.

On Jan. 10, The New York Times reported that several women had accused Mr. Helmer of making advances toward them in the workplace during his time at the Philadelphia museum. On Jan. 12, the Erie Art Museum forced Mr. Helmer to resign.

Mr. Helmer, who did not respond to a request for comment, has denied any misconduct but declined to discuss his relationships with female employees.