Graphene is 2-dimensional carbon nanomaterials with sp2 hybrid bondings like graphite, carbon nanotube, and fullerene. Since its isolation methods from graphite were developed, it has been studied by a number of researchers from academic area to engineers developing the applications. Graphene possesses outstanding electrical, thermal, and optical properties. In addition, it has been suggested the applications of flexible electronics and structural materials due to its superior mechanical properties. Especially, fracture characteristics of graphene are significant for the development of graphene-based flexible electronic devices and composite materials. However, fracture characteristics of graphene have not been understood until now, since its thickness of nanoscale makes the specimen fabrication and the mechanical test for characterizing fracture properties. In this study, we developed fracture testing method for graphene freestanding tensile specimen and obtained fracture characteristics by fracture mechanics test in a scanning electron microscope. By in-situ fracture test, we obtained load-displacement curve and in-situ fracture image during the test. Fracture toughness derived from the test results using finite element analysis and discussed the fracture behavior of graphene. This results can contribute a development of various graphene-based applications.