The worker, who was employed by a subcontractor of the Qatalum project, was buried by soil when the side of an excavation collapsed.
The incident is currently under police investigation. The Qatalum owners have established a joint committee to carry out a separate investigation.
Qatalum, a joint venture between Hydro and Qatar Petroleum, is building a large aluminium smelter in Qatar. There are currently around 17,000 people working at the site.