In this paper, the joint strength of lap jointed CFRP laminate manufactured by VARTM process was evaluated. Unlike the adhered joint, manufacturing of the lap joint with VARTM can be conducted in one-process, which means that the secondary processing like sanding and adhesion is unnecessary. Three types of joint configuration were adopted in this study ; single-lap, double-lap and scarf-lap joints. First, the effectiveness of one-process molding of single-lap joint was evaluated comparing with the adhered joint. The joint strength of one-process molded joint was about 80％ higher than that of adhered joint. In one-process manufacturing, the joint strength of scarf-lap joint was about 100％ higher than that of single-lap joint. Next, the stress condition in lap joint specimen was evaluated to discuss the fracture mechanism of joint structure with Finite element analysis. FEM results showed good agreement with experimental data. Finally, the energy release rate at the tip of lap surface was calculated by FEM in order to clarify the mechanism of the initiation of delamination.
