a bottom plate;

a module having two surfaces facing each other;

a plurality of optical fibers, each of which is connected to the module via at least one of the surfaces of the module;

a plurality of reels which are sequentially stacked on an upper surface of the bottom plate, each of the plurality of reels accommodating a bundle of one corresponding optical fiber among the plurality of optical fibers, wherein the module is disposed in a space formed inside the plurality of reels which are stacked, and

wherein the reel includes a body portion extending in a stacking direction of the plurality of reels, and a flange portion formed at a position close to one end of the body portion in an extending direction of the body portion and extending toward an outer side of the body portion in a direction intersecting the extending direction; and

a plurality of pillars extending in the stacking direction of the plurality of reels and spaced apart from each other in a direction intersecting the stacking direction,

wherein a plurality of holes are formed in the body portion of the reel, a corresponding pillar being inserted into each of the plurality of holes.