The invention relates to a light source device having a high-voltage discharge lamp (1) on which a trigger line (10) for triggering the lamp is attached. The high-voltage discharge lamp (1) is formed such that an arc tube (7) having a pair of substantially cylindrical sealing portions (9R, 9L) formed on both sides in the longitudinal direction with a light emitting portion (8) in between is sealed with electrode assemblies (3R, 3L). The trigger line (10) is formed such that its one end (10a) is connected to a power supply lead (6), which is of the electrode assembly (3L) and protruded from the one sealing portion (9L), and its other end (10c) is wound around the outer circumference of the other sealing portion (9R). In the light source device, in order to drastically improve the performance for triggering and retriggering the lamp (1), a vicinity guide portion (C) including a hollow groove (11) and an insert opening (17) is formed on a cylindrical portion of the other sealing portion (9R) at a position away from the light emitting portion (8). The vicinity guide portion (C) allows the trigger line (10) to be disposed at a distance shorter than the distance from the electrode assembly to the outer circumference surface of the cylindrical portion.