A reflector used in an electronic flash device that collectively emits direct light emitted from a light source and reflected light that has been reflected by a reflective surface onto a subject, and an electronic flash device that uses such reflector. The reflector includes a pair of first reflective surfaces that are composed of portions of a cylindrical curved surface and face one another, and a second reflective surface that is contiguous with the pair of first reflective surfaces and inside which a xenon lamp is housed. Contiguous portions where the pair of first reflective surfaces and the second reflective surface are contiguous are set closer to the opening of the pair of first reflective surfaces than a center of the xenon lamp. With this construction, by it is possible to maintain a predetermined optical performance while making the electronic flash device smaller and slimmer.