An illumination optical unit (26A, 26B, 80) for an endoscope comprising: an optical fiber (37A, 37B) for guiding a laser beam supplied from a laser beam source to a distal end of the optical fiber and emitting the guided laser beam from the distal end; a fluorescent body that is excited by the laser beam emitted from the optical fiber to emit fluorescent light and that forms white light consisting of the fluorescent light and the laser beam; a holding member that holds the fluorescent body, has a fluorescent body holding portion opened on a distal end side, and a through hole that is continuous from a proximal end of the fluorescent body holding portion and allows the optical fiber to be inserted therethrough, and is formed in a substantially cylindrical shape; a sleeve member (81, 82) that has an inner peripheral face fitted to an outer peripheral face of the holding member and has a distal end and a proximal end opened; and a protective cover that is held by the sleeve member (81, 82), covers the distal end side of the fluorescent body, and transmits the fluorescent light and the laser beam, wherein the optical fiber is made to protrude from the proximal end of the holding member and the sleeve member (81, 82), the distal end side of the fluorescent body is sealed by bonding the sleeve member (81, 82) and the protective cover, and a proximal end side of the fluorescent body is sealed by bonding the sleeve member (81, 82) and the holding member, and the sleeve member (81, 82) includes a first sleeve member that holds the protective cover, and a second sleeve member combined with a proximal end side of the first sleeve member, wherein the bonding the sleeve member and the protective cover includes the first sleeve member and the protective cover being bonded with an adhesive, wherein the bonding the sleeve member (81, 82) and the holding member includes the holding member and the first sleeve member being bonded together by means of an adhesive, wherein a proximal end face of the first sleeve member and a distal end face of the second sleeve member are bonded together by means of an adhesive. an optical fiber (37A, 37B) for guiding a laser beam supplied from a laser beam source to a distal end of the optical fiber and emitting the guided laser beam from the distal end; a fluorescent body that is excited by the laser beam emitted from the optical fiber to emit fluorescent light and that forms white light consisting of the fluorescent light and the laser beam; a holding member that holds the fluorescent body, has a fluorescent body holding portion opened on a distal end side, and a through hole that is continuous from a proximal end of the fluorescent body holding portion and allows the optical fiber to be inserted therethrough, and is formed in a substantially cylindrical shape; a sleeve member (81, 82) that has an inner peripheral face fitted to an outer peripheral face of the holding member and has a distal end and a proximal end opened; and a protective cover that is held by the sleeve member (81, 82), covers the distal end side of the fluorescent body, and transmits the fluorescent light and the laser beam, wherein the optical fiber is made to protrude from the proximal end of the holding member and the sleeve member (81, 82), the distal end side of the fluorescent body is sealed by bonding the sleeve member (81, 82) and the protective cover, and a proximal end side of the fluorescent body is sealed by bonding the sleeve member (81, 82) and the holding member, and the sleeve member (81, 82) includes a first sleeve member that holds the protective cover, and a second sleeve member combined with a proximal end side of the first sleeve member, wherein the bonding the sleeve member and the protective cover includes the first sleeve member and the protective cover being bonded with an adhesive, wherein the bonding the sleeve member (81, 82) and the holding member includes the holding member and the first sleeve member being bonded together by means of an adhesive, wherein a proximal end face of the first sleeve member and a distal end face of the second sleeve member are bonded together by means of an adhesive.