In a lamp device provided with an arc tube, a principal reflection mirror, and a sub-mirror; a decrease in illumination light, caused by a trigger line disposed to improve the turn-on characteristics of the arc tube, being suppressed. The lamp device include an arc tube having a bulb portion that incorporates electrodes and sealing portions; a principal reflection mirror; a sub-mirror; leads connected to an electrode at an end portion of each of the sealing portions; and a trigger line. The trigger line has a ring-like portion wound around the sealing portion. The trigger line extends from the ring-like portion and has a wiring path that passes a neighborhood of the bulb portion without coming into contact with the bulb portion, further extends along the sealing portion and is connected to the lead. The wiring path is in the same plane that extends through an optical axis.