High contention and energy absorption capacity system to contain vehicle's side impact configured by an anchoring plate, configured by a post having a base, a frontal plate and a base plate and said post affixed to the terrain at regular intervals, configured by two or more systems of continuous horizontal rails arranged longitudinally and attached to the post by a clamp placed in the inner side of the rail and also constituted by a separating device that is characterized by the post's leg to be comprised by two tubular profiles, mutually facing, the base plate of the post having frontal and lateral-rear openings that permit a certain controlled displacement of the post's leg, as a separating device between the post and the rail there is a shock-absorbing system having high energy capacity that serves to endow the system with a high capacity to absorb the energy resulting from the impact of a vehicle and allow it to be redirectioned.