A wind turbine blade used in a wind power generator that receives wind and rotates a rotating shaft of a generator includes at least two layers on a surface of a blade body, one of the layers being colored with a coating material different in color from the blade body and the rest of the layers. The layers are provided at least on a tip, particularly at a front edge of the wind turbine blade. A wind turbine blade monitoring system that monitors the wind turbine blade includes: an imaging unit that images the wind turbine blade in a predetermined position over a predetermined period at timing when the wind turbine blade passes through the predetermined position; and an indication unit that chronologically indicates imaging results of the wind turbine blade imaged by the imaging means.