A field-effect transistor comprises, on a substrate, a source electrode, a drain electrode, and a gate electrode; a semiconductor layer in contact with the source electrode and the drain electrode; wires individually electrically connected to the source electrode and the drain electrode; and a gate insulating layer that insulates the semiconductor layer from the gate electrode, wherein a connecting portion between the source electrode and the wire forms a continuous phase, and a connecting portion between the drain electrode and the wire forms a continuous phase, the portions constituting the continuous phases contain at least an electrically conductive component and an organic component, and integrated values of optical reflectance at a region of a wavelength of 600 nm or more and 900 nm or less on the wires are higher than integrated values of optical reflectance at a region of a wavelength of 600 nm or more and 900 nm or less on the source electrode and the drain electrode.