Discoloration and deformation of a resin case triggered by heat generation from a failed circuit component at the end of the life of an arc tube are prevented without increasing the cost and size. A lighting unit that lights a light source with an inverter while receiving electric power from an AC power supply, and that contains a lighting circuit that includes a plurality of circuit components inclusive of capacitors. Among the capacitors, all capacitors with an applied voltage of 50V or greater (C4, C5, C6, C7, C8, CD1 and CD2) are foil type film capacitors with exceptions of smoothing electrolytic capacitors (CD1 and CD2).