A protective helmet, particularly for sports and work use, including a rigid outer shell which itself comprises a front cap having a concavity able to cover at least the upper part of the cranium, and a rear cap having a concavity able to cover the rear part of the cranium. The caps are mutually movable, the rear cap being connected to the front cap in such a manner as to rotate relative to the front cap about an axis transverse to the vertical plane of symmetry of the cranium, between a raised position and a lowered position.