This report studies the behavior of wooden hardboard webed I-beam under proportional or reverse cyclic loading. I have been investigated to the following results by the experimental study. The slippage of joint surface between web-plate and flange memberes is due to the reduction of strength and toughness, and be due to the redistribution of the bending stresses from the web to the flanges at each cross sections of I-beam. The specimens consist of two types, Type I (beam span 150cm, depth 18cm, 1980) and Type II (beam span 360cm, depth 30cm, 1982). According to this experimental result, it becomes clear that there are few characteristics on the wooden composite I-beames under revers cyclic loading : (1) REDUCED MOMENT OF INERTIA I_R is expressed the beam strength in the yield stage, that is plastic domain to failure state. (2) The phenomenon of the REDISTRIBUTION is described by concept of the SEPARATE POINT SP. When a load exceed separate point the stress redistribution takes remarkable effect and the solid type convert to the separate type. The state of separate point is indicated Fig.12, 13. (3) The relation between the damping capacity E_d which calculate by hysteresis loops under reverse cyclic loading and the residual deflection Δ_r in each cyclic hysteresis loop, have described the characteristic maps. These E_d-Δ_r maps are valuable indicator to estimate the ultimate toughness and aseismatic property of the hardboard composite webed I-beam.