The invention relates to a shock absorption device making it possible to tilt the back of a seat frontward in case of a shock greater than a predetermined value, the device including a plate and an absorbing shaft, the plate including a brake cavity and a hole through which the absorbing shaft passes, the hole and the brake cavity being separated by a bridge, and the dimensions of the bridge being such as to break when the stress exerted on the back is greater than a predetermined value. The invention also relates to a seat for a passenger vehicle and, more particularly, an aircraft, the pivotal rotation of which is provided with such a device.