Abstract: A shock absorptive support structure in a coupler, improved in both economical efficiency and in practical usefulness, so that a shock due to relative displacement between a top plate and support brackets occurring in a vertical direction as well as in a back and forth direction can be effectively absorbed by the structure, driving comfort can be assured, wear of elastic members can be minimized, and a high measure of driving safety can be maintained for a long period of time with the structure of simplified construction enabling the manufacturing cost to be reduced. Shock absorbing members each include an inner cylinder, an outer cylinder and an elastic member disposed between these two cylinders and through which respective axle pins extend rotatably, and are tightly inserted into bearing holes of respective support brackets.