A thin film transistor includes: an insulation substrate; a semiconductor layer formed on the insulation substrate including, conductive regions that includes impurity, and a channel region sandwiched between the conductive regions; an insulation layer that covers the semiconductor layer; a gate electrode that is formed on the insulator layer at a position where opposes the channel region; and a source electrode and a drain electrode connected to the conductive regions. The channel region divided into a plurality of channel regions and each of channel widths of the plurality of channel regions is in a range from 5 .mu.m to 30 .mu.m.
