This paper describes hydroelastic motion and effect of motion reduction of large floating structures in head sea conditions, supported by aircushion. Motion reduction effects, appearing due to the presence of aircushions, have been confirmed through theoretical calculations with the zero-draft assumption. Three-dimensional prediction method has been developed for evaluating draft influence of division walls of aircushions. Using three-dimensional theoretical calculations, authors have investigated whether hydroelastic motion reduction is possible or not. Next, aircushion type bodies were supported by multiple aircushions, which are smaller in size than the wavelengths. Green’s function method within the linear potential theory was applied for prediction of hydrodynamic forces and wave excitations, in which the effect of free water surface between aircushions was considered. Hydroelastic responses were estimated not only in terms of elastic motion, but also in terms of vertical bending moment. The results confirmed the existence of response reduction, especially noticeable for the vertical bending moment in a wide wavelength range and in the whole structure area.