Provided is a hydrogen generator capable of suppressing degradation in capability of a hydrogen generator which is caused by crush of particulate reforming catalyst and of suppressing decrease in reforming efficiency due to decrease in heat transfer efficiency of a catalyzing portion which is caused by the crush of the particulate reforming catalyst. A hydrogen generator comprises a catalyzing portion 50 having particulate reforming catalyst P, and a combusting portion 5 for heating the catalyzing portion 50, the hydrogen generator being configured to generate a reformed gas containing hydrogen while flowing a material gas containing steam in a direction in which the catalyzing portion 50 extends. The catalyzing portion 50 includes a separating member 40. The separating member 40 is disposed on a separating cross-section which is a cross-section of the catalyzing portion 50 in a direction perpendicular to the direction in which the catalyzing portion 50 extends. A plurality of air holes 40D having a shape to inhibit passage of the particulate reforming catalyst P are provided on the separating member 40. An opening having a shape to permit passage of the particulate reforming catalyst P is provided on the separating cross-section.