A thin-film transistor includes a source electrode, a drain electrode arranged apart from the source electrode, an organic semiconductor layer arranged between the source electrode and the drain electrode so as to establish connection of the source electrode and the drain electrode, a first insulating layer arranged on one surface side of the organic semiconductor layer, a gate electrode arranged on a side of the first insulating layer opposite that on which the organic semiconductor layer lie, and a second insulating layer arranged on a side of the organic semiconductor layer opposite that on which the first insulating layer lie. The organic semiconductor layer contains an organic semiconductor material having p-type semiconducting properties. The second insulating layer contains one or more compounds of the following formula (1), so that electrons are fed from the second insulating layer into the organic semiconductor layer:wherein R1 and R2 independently represent a substituted or unsubstituted alkylene group; X1, X2, X3 and X4 each represent a hydrogen atom or an electron-donating group; and n represents 100 to 100,000, wherein at least one of X1, X2, X3 and X4 represents an electron-donating group.