The present invention provides a step in which a channel-length of a TFT can be controlled with higher reproducibility. In addition, the present invention provides a step in which a short channel-length of the TFT can be manufactured. Further, the present invention provides a structure of the TFT in which a current-voltage characteristic can be improved. The present invention refers to a thin film transistor comprising a lamination layer wherein a first conductive film, a first insulating film and a second conductive film are sequentially laminated, a semiconductor film formed so as to be in contact with the side surface of the lamination layer, and a third conductive film covering the semiconductor film through a second insulating film. The first conductive film and the second conductive film are a source electrode and a drain electrode, and a region which is in contact with the first insulating film and the third conductive film is a channel forming region in semiconductor film, and the third conductive film is a gate electrode.