Embodiments of the invention provide a thin film transistor substrate, comprising: an insulating substrate; a gate wire formed on the insulating substrate; a first gate insulating layer made of an inorganic material, formed on the gate wire and having a first insulating layer contact hole for exposing at least a part of the gate wire; a second gate insulating layer made of an organic material, formed on the first gate insulating film and having a second insulating layer contact hole corresponding to the first insulating layer contact hole; a source electrode and a drain electrode formed on the second gate insulating layer and being aparted from each other to be defining a channel area; and an organic semiconductor layer formed on the channel area.Accordingly, the present invention provides an organic TFT substrate in which a characteristic of a TFT is improved.