Abstract: A heating furnace (561) comprises an inner cylindrical part (601) adapted to rotate about a predetermined axis (C1), a cover part (581) containing the inner cylindrical part therewithin and being capable of confining heat therewithin, and a heat supply part (92) for supplying the heat into the inner cylindrical part. The inner cylindrical part includes a first end part (65A1) located on one end side of the predetermined axis, a second end part (65B1) located on the other end side of the predetermined axis, and a plurality of connecting members (661) for connecting the first and second end parts to each other and circulating an object within the inner cylindrical part as the inner cylindrical part rotates. The plurality of connecting members are discretely arranged circumferentially so as to form an opening (691) between the connecting members adjacent to each other.