Healy's method commonly employed in wave reflection tests is only the first order approximation and gives an apparent vulue of reflection coefficient, which may be smaller than one-half of the true value. Six diagrams for the correction of apparent reflection coefficient have been prepared for the relative dopth of h/L=0.08, 0.10, 0.12, 0.15, 0.20 and 1.0 based on the third order theory of partical standing waves developed. The diagrams also present the correction to the apparent height of incident waves based on Hearly's method; the apparent height may be as large as 1.5 times the true incident wave height. The applicability of these diagrams has been verified by the experiment conducted for the wave reflection from a vertical wall and energy dissipators. The theory also predicts the increase of standing wave height over twice the height of incident wave height.