Disclosed is a thin film transistor wherein an ON current is increased and a leak current is reduced. The channel layer 60 of the TFT 10 is formed of a crystalline silicon, and the lower surface of one end of the channel layer 60 is electrically connected to the surface of an n+ silicon layer 40a, and the lower surface of the other end is electrically connected to the surface of an n+ silicon layer 40b. Furthermore, the side surface of said end of the channel layer 60 is electrically connected to a source electrode 50a, and the side surface of the other end is electrically connected to a drain electrode 50b. Thus, a barrier that makes electrons, which act as carriers, not easily transferred is formed on the boundary between the source electrode 50a and the channel layer 60. As a result, the ON current that flows when the TFT 10 is in the ON state can be increased, and the leak current that flows when the TFT is in the OFF state can be reduced.