An electronic circuit device includes a plurality of logic circuit elements which output an output signal by performing a preset operation on an input signal. Transistors constituting the logic circuit elements each have a gate electrode provided on a substrate, an insulating layer electrically insulating the gate electrode, a source electrode, a drain electrode, and a semiconductor layer. Input signal wiring, to which the input signal is applied, is connected to the gate electrode and provided inside the insulating layer on the substrate. Output signal wiring, from which the output signal is taken out, is connected to the source electrode or the drain electrode and provided inside the insulating layer on the substrate. An electronic circuit performing a preset processing is constituted with the plurality of logic circuit elements.