Abstract: A cooling channel structure includes a tubular member with openings at both ends. In an inner portion or on a surface of the tubular member, as cooling channels for flowing a cooling medium for cooling the tubular member, provided are a plurality of spiral outer surface-side channels located on an outer surface side of the tubular member, at least one inner surface-side channel located on an inner surface side of the tubular member, and a plurality of folded channels, respectively, connecting the plurality of outer surface-side channels and the at least one inner surface-side channel on one end side of the tubular member.

Abstract: Provided are a first wall section extending along a first direction, a second wall section disposed at an interval from the first wall section in a second direction orthogonal to the first direction, and a plurality of partition wall sections connecting the first wall section and the second wall section so as to form at least one cooling channel between the first wall section and the second wall section, the cooling channel having a plurality of channel cross-sections disposed at intervals in the first direction. In a cross-section including the first direction and the second direction, at least a part of each of the partition wall sections extends along a direction intersecting with the second direction.