The element is for use in a crash barrier (1) made up of a vertical support post (2) and a double-wave cross-beam (3), and comprises substantially vertical parallel rotary bearings (5), an upper upright (6) located above the bearings (5), to which said bearings (5) are connected, an absorption plate (8) made up of two zigzag arms (9) joined via a central sector (10), attached to the upper upright (6), a metal impact-absorption structure (13) positioned longitudinally along the barrier (1), at the bottom of the bearings (5), and between the bearings (5) and the vertical support post (2), a first connection bracket (11) connecting the absorption plate (8) to the vertical support post (2), and a second connection bracket (12) connecting the metal absorption structure (13) to the vertical support post (2). A crash barrier (1) incorporating the protection element (4).