Disclosed is a method for fabricating a high-performance field-effect transistor biosensor for diagnosing cancers using micro conductive polymer nanomaterials funtionalized with anti-VEGF aptamer. Disclosed is a high-sensitivity field-effect transistor biosensor for diagnosing cancers using a micro conductive polymer nanomaterial transistor array including a micro polymer nanomaterial transistor array including a channel region provided with a metal source electrode, a metal drain electrode, a gate and micro polymer nanomaterials, and an anti-VEGF aptamer covalently bound to the surface of the micro polymer nanomaterials constituting the channel region of the micro polymer nanomaterials transistor array, to target VEGF (Vascular endothelial growth factor).