LIGHT SOURCE DEVICE AND PROJECTOR

PROBLEM TO BE SOLVED: To provide a projector which ensures a long life of a luminous tube.SOLUTION: A projector 1 comprises: a luminous tube having a luminous part in which a pair of electrodes are disposed; a cylindrical body 13 surrounding the luminous tube; and a cooling device 5 for cooling the luminous tube. The cylindrical body 13 includes a first side wall part 131 and a second side wall part 132 adjacent to each other in a circumferential direction of the cylindrical body 13. In the first side wall part 131 and the second side wall part 132, ventilation openings for sending air toward the luminous part are provided, respectively. The cooling device 5 includes a cooling fan 51 which sucks and discharges air, and a first duct 531 and a second duct 532 which are respectively attached to the first side wall part 131 and the second side wall part 132, extend in the circumferential direction of the cylindrical body 13 from respective ends where the air from the cooling fan 51 is introduced so as to separate from each other, and guide the air introduced from the respective ends to the respective ventilation openings.