Circuit board and display device

A circuit board comprising:

• a first transistor element including a first semiconductor layer serving as a channel layer;
• a second transistor element including a second semiconductor layer serving as a channel layer;
• and
• a first conductive layer, a second conductive layer and a third conductive layer as electrode formative layers by which the first transistor element and the second transistor element are formed,
• the first transistor element and the second transistor element being provided on one surface of a single insulating substrate,
• the first conductive layer forming one of a gate electrode and a pair of source and drain electrodes of the first transistor element,
• the third conductive layer forming one of a gate electrode and a pair of source and drain electrodes of the second transistor element,
• the second conductive layer forming both of (a) the other one of the gate electrode and the pair of source and drain electrodes of the first transistor element and (b) the other one of the gate electrode and the pair of source and drain electrodes of the second transistor element,
• one of the first conductive layer and the third conductive layer being formed above the second conductive layer in a thickness direction in which the first conductive layer, the second conductive layer, and the third conductive layer are stacked on the insulating substrate,
• the other one of the first conductive layer and the third conductive layer being formed below the second conductive layer in the thickness direction in which the first conductive layer, the second conductive layer, and the third conductive layer are stacked on the insulating substrate.