Composite slab with steel plate and reinforced concrete has excellent mechanical properties. Fabrication of long footing is possible by the advantage of this merit. Large value of sectional forces are given at the fixed edge of the footing due to ground reaction and so on. Design of the footing is usually carried out as a cantilever beam. Mechanical behaviour of the footing subjected to large sectional force is not confirmed. Especially, force transmission mechanism to the adjacent members and effect of alternative loading are not enough made clear. Loading tests for model test specimens are carried out to know these mechanical properties and to investigate the validity of design calculation. Through these loading tests, enough strength is obtained for the composite footing. However, shear strength of the specimen with reinforcing bars as shear reinforcement is small becouse truss mechanism is not developed at the fixed edge of the composite footing. On the other hand, the specimen with angle has enough shear bearing capacity. It is also necessary to consider the force transmission to adjacent members for design of the caisson.