A thin film transistor comprising: a flexible substrate having a support surface; a gate electrode layer located in a first part (11S1) of the support surface; a gate insulating layer (21, 22) covering a second part (11S2) of the support surface and the gate electrode layer; a semiconductor layer sandwiching the gate insulating layer (21, 22) with the gate electrode layer; a source electrode layer in contact with a first end of the semiconductor layer with no insulating layer between the source electrode layer and the semiconductor layer; and a drain electrode layer in contact with a second end of the semiconductor layer with no insulating layer between the drain electrode layer and the semiconductor layer, wherein the gate insulating layer (21, 22) includes a first gate insulating coating made of an organic polymer compound or an organic-inorganic composite material and covering the second part (11S2) and the gate electrode layer, and a second gate insulating coating made of one selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide, and sandwiched between the first gate insulating coating and the semiconductor layer, and the first gate insulating coating has a thickness of 100 nm or greater and 1500 nm or less, a product of the thickness and Young's modulus of the first gate insulating coating is 300 nm·GPa or greater and 30000 nm·GPa or less, the second gate insulating coating has a thickness of 2 nm or greater and 30 nm or less, and a product of the thickness and Young's modulus of the second gate insulating coating is 100 nm·GPa or greater and 9000 nm·GPa or less. a flexible substrate having a support surface; a gate electrode layer located in a first part (11S1) of the support surface; a gate insulating layer (21, 22) covering a second part (11S2) of the support surface and the gate electrode layer; a semiconductor layer sandwiching the gate insulating layer (21, 22) with the gate electrode layer; a source electrode layer in contact with a first end of the semiconductor layer with no insulating layer between the source electrode layer and the semiconductor layer; and a drain electrode layer in contact with a second end of the semiconductor layer with no insulating layer between the drain electrode layer and the semiconductor layer, wherein the gate insulating layer (21, 22) includes a first gate insulating coating made of an organic polymer compound or an organic-inorganic composite material and covering the second part (11S2) and the gate electrode layer, and a second gate insulating coating made of one selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide, and sandwiched between the first gate insulating coating and the semiconductor layer, and the first gate insulating coating has a thickness of 100 nm or greater and 1500 nm or less, a product of the thickness and Young's modulus of the first gate insulating coating is 300 nm·GPa or greater and 30000 nm·GPa or less, the second gate insulating coating has a thickness of 2 nm or greater and 30 nm or less, and a product of the thickness and Young's modulus of the second gate insulating coating is 100 nm·GPa or greater and 9000 nm·GPa or less.