A rotating drum (1) has an integration concave (2) on the outer circumference surface, and is provided with a drum main body (3) and an air-permeable opening member (4) forming the bottom surface (2A) of the integration concave (2). The opening member (4) is sandwiched between an exterior forming member (6) disposed facing the bottom surface (2A) and an interior forming member (7) disposed between the opening member (4) and the drum main body (3), and both forming members (6, 7) are disposed so as to overlap with the opening member (4). The concave bottom-surface corresponding parts (6A, 7A) of the forming members (6, 7) that overlap with the bottom surface (2A) of the integration concave (2) in planar view are configured from multiple openings (65, 75) penetrating the concave bottom-surface corresponding parts (6A, 7A) in the thickness direction and from opening defining parts (60, 70) for dividing and forming the openings (65, 75). The opening defining part (70) of the interior forming member (7) corresponds to the opening defining part (60) of the exterior forming member (6).La présente invention concerne un tambour rotatif (1) comprenant un élément d'intégration concave (2) sur la surface de la circonférence externe, ainsi qu'un corps principal de tambour (3) et un élément d'ouverture perméable à l'air (4) formant la surface inférieure (2A) de l'élément d'intégration concave (2). L'élément d'ouverture (4) est intercalé entre un élément formant l'extérieur (6) disposé face à la surface inférieure (2A) et un élément formant l'intérieur (7) disposé entre l'élément d'ouverture (4) et le corps principal de tambour (3), et les deux éléments de formation (6, 7) sont disposés de sorte à chevaucher l'élément d'ouverture (4). Les parties (6A, 7A) correspondant à la surface inférieure concave des éléments de formation (6, 7) qui chevauchent la surface inférieure (2A) de l'élément d'intégration concave (2) dans une vue plane sont configurées à partir de multiples ouvertures
