A semiconductor device (100A) is provided with: a gate electrode (3); an oxide semiconductor layer (5); a thin-film transistor (101) including a gate insulating layer (4), a source electrode (7S), and a drain electrode (7D); an inter-layer insulating layer (11) arranged so as to cover the thin-film transistor (101) and come into contact with a channel area (5c) of the thin-film transistor (101); and a transparent electroconductive layer (19) arranged on the inter-layer insulating layer (11), the source electrode (7S) and the drain electrode (7D) each having a copper layer (7a), and the device being further provided with a copper oxide film (8) arranged between the source and drain electrodes and the inter-layer insulating layer (11). The inter-layer insulating layer (11) covers the drain electrode (7D) with the copper oxide film (8) interposed therebetween. The transparent electroconductive layer (19) is directly connected to the copper layer (7a) of the drain electrode (7D) inside a contact hole (CH1) formed in the inter-layer insulating layer (11), without the copper oxide film (8) being interposed therebetween.