Road safety barrier (10) usable in correspondence with a roadway and consisting of modular elements (11), each of which comprises a skirt (20, 120) having a front surface (27) facing towards the roadway. Each modular element (11) comprises at least a metal upright (12) which lies on a substantially vertical plane and is anchored to the roadway. The skirt (20, 120) is attached on the metal upright (12) in order to arrange, during use, the front surface (27) facing towards the roadway; the metal upright (12) comprises two lateral flanks (13) which diverge towards the front surface (27), and are joined together in a rear zone (35), distant from the front surface (27).