We report on results of fluid flow in a single fracture obtained from combination technique of physical experiments and flow simulation for investigating effects of asperity degradation due to sliding of fracture on flow properties of a fracture. We conducted sliding experiments of a rock fracture using cylindrical granite specimens (60 mm in diameter, 140 mm in axial length) containing a single tensile fracture. Sliding along the fracture was made by controlling a loading piston at constant rate of 0.001 mm/s under constant confining pressure of 5 MPa. Sliding displacement was applied up to approximately 6 mm along the surfaces. During the sliding, fluid flow was made within the fracture by applying a constant fluid pressure differential of 0.1 MPa through boreholes of 3 mm diameter drilled in the specimens. Fracture permeability was evaluated at every 0.5 mm in axial displacement by measuring the pressure differentials between inlet and outlet of the fluid and mass flow at the outlet. Flow field within the fracture is calculated with flow simulation in which based on the measured fracture permeabilities, which shows that major flow paths can significantly change with sliding even at the almost constant permeability during sliding. Our result suggests that the change in flow field with shearing may have important roles in material transport due to advection, which could affect physical strength of a fracture by water-rock interactions on fracture surfaces such as precipitation and/or dissolution.