A thin film transistor according to an embodiment of the present invention includes: a semiconductor layer formed on a substrate and having a first diffusion region, a channel region, and a second diffusion region; a gate electrode opposite to the semiconductor layer across a gate insulating film formed on the semiconductor layer; and a connecting conductive film formed on the semiconductor layer opposite to the gate insulating film and extending from the first diffusion region up to a predetermined position in the channel region to electrically connect between the first diffusion region and the channel region. The transistor further includes a laying conductive layer formed on the semiconductor layer opposite to the gate insulating film and electrically connected with the second diffusion region.