Statoil Chief Executive Office Helge Lund said it was with "deep sorrow" that he confirmed the death of Victor Sneberg, Statoil country manager in Algeria.
Sneberg is the fifth confirmed fatality from the attack for Statoil.
Terrorists sympathetic to al-Qaida in the Islamic Maghreb stormed the In Amenas natural gas facility in eastern Algeria last month. The complex is operated by BP, Statoil and state energy company Sonatrach.
BP this week said three of its employees died in the Jan. 16 attack.
The attack was said to be a response to an Algerian decision to let French forces use their airspace for a multilateral intervention in Mali, where al-Qaida occupies territory.
BP started natural gas production at the facility in 2006. The company said production there was targeted at around 870 million cubic feet per day, making it the largest facility of its kind in Algeria.
Algeria, Tunisian and Libyan forces were deployed to ensure the safety of their energy sectors.