Recently, Carbon Fiber Reinforced Plastic (CFRP) composites are applied to pressure equipment such as pressure vessels and pressure pipes, etc., not only aircraft structure. When pressure equipment or aircraft structure like that made of CFRP laminate composite material are damaged, one of the repair treatments is the bonded repair.<br>In this study, focusing on the repair treatment with scarf joint which is a bonded repair method and used also for the repair of the aircraft structure damage, the tensile strength and fatigue strength of the bonded scarf joints were examined by using the two-dimensional scarf joint specimens which simulate the cross-section of an actual repaired part with scarf joint with flat conical shape. Furthermore, the residual tensile strength and the residual fatigue strength after impact loading were evaluated by using the bonded scarf joint specimen with impact loading damage. The following results are obtained.<br>⑴ Larger scarf angle of the bonded CFRP scarf joint has lower tensile strength. ⑵ The doubler patches are effective in the tensile strength improvement of bonded CFRP scarf joint, the tensile strength of the scarf joint is reinforced about 7 to 10 % by attaching doubler patches. ⑶ σ_R−N_f curves for base material of CFRP laminate composite, the bonded CFRP scarf joints with scarf angle 2 degrees and 6 degrees, and the scarf joints of scarf angle 2 degrees attached doubler patches were obtained. ⑷ The tensile strength of the bonded CFRP scarf joint with scarf angle 2 degrees decreases about 6 to 9% after impact loading with 30.5 J. ⑸ The effect of impact loading with 30.5 J on the fatigue strength of the bonded CFRP scarf joints, which scarf angle is 2 degrees, with and without doubler patches was within the variability of the measured data. ⑹ In case of the bonded repair treatment with the scarf joint, the scarf angle as small as possible is preferred from comparison between the scarf angle 2 degrees and 6 degrees.