During VaRTM (Vacuum assisted Resin Transfer Molding) a distribution medium which is incorporated on fiber preform as a surface layer is used to shorten impregnation time of resin by increasing the flow rate of resin and is removed after molding. In this study, the distribution medium is replaced by a thermoplastic polyamide mesh, and the mesh is still remained in the fiber preform after VaRTM process. The mesh is expected to improve not only the resin flow but also interlaminar toughness in the composite laminates after molding. Multipoint measurements for resin flow during VaRTM process are carried out by using embedded fiber optic sensors. It is confirmed that the polyamide mesh inserted in the fiber preform increased the flow rate during the impregnation of resin. ENF tests using with specimens which have bonded doubler plates to both top and bottom surfaces are carried out. The crack length can be predicted by a simple beam theory. ENF tests have been found that GIIC are improved by inserting the polyamide mesh. From these results it is shown that improvements in both resin flow and interlaminar toughness can be achieved by the single action of inserting the polyamide mesh.