A thin film transistor is provided. The thin film transistor includes a gate, at least an inorganic material layer, at least one dielectric layer, a source, a drain, and an active layer. The active layer is located on the substrate. The source and the drain cover a part of the active layer and a part of the substrate. A channel region exists between the source and the drain. The inorganic material layer is filled into the channel region. The dielectric layer at least including an organic material covers the inorganic material, the source and the drain. The gate is disposed on the dielectric layer.