The present invention provides an organic thin film transistor substrate and a method of manufacturing the same capable of uniformly forming the thickness of a gate insulating layer and a protective layer and preventing overflow of an organic semiconductive layer.The organic thin film transistor according to the present invention comprises a gate line formed on a substrate; a data line which intersects the gate line with an organic gate insulating layer interposed therebetween to define a pixel area; a thin film transistor connected with the gate line and the data line and which includes an organic semiconductive layer; a pixel electrode connected with the thin film transistor and formed in the pixel area; an organic protective layer formed parallel with the gate line to cover the organic semiconductive layer and its peripheral area; a first border insulating layer stepwise formed so that the organic gate insulating layer and the protective layer are filled, and a second border insulating layer formed on the source electrode and the drain electrode of the thin film transistor so that the organic semiconductive layer is filled.