The present invention relates to a shock absorption device of a safety plate for a shrub trimmer provided with a safety plate mounted on the lower portion of a blade in order to protect the blade, and provides a shock absorption device of a safety plate for a shrub trimmer, comprising: an upper safety plate support member formed at the upper portion of a safety plate for supporting a blade; and a lower safety plate support member coupled to the upper safety plate support member for supporting the safety plate; wherein safety plate rotation-restraining means are formed to correspond to each other on an inner periphery of a through hole of the safety plate and an outer periphery of the upper safety plate support member or the lower safety plate support member, and a rotation preventing die is fixed to a handle in order to prevent the rotation of the lower safety plate support member. According to the present invention, if a shock generated by a collision between the blade and debris is transmitted to the safety plate, by the safety plate and the upper safety plate support member or the lower safety plate support member provided with the safety plate rotation-restraining means, concave grooves of the rotation-restraining means move over elastic protrusions corresponding to each other such that the safety plate rotates in the direction that the shock is applied. Therefore, the shock is absorbed and the debris is deflected simultaneously, thereby preventing damage to the blade or the safety plate.