A filler for a multicore cable comprising: a frame part including a first frame part and a second frame part which are symmetric to each other; a rotating part configured to connect the first frame part and the second frame part; cut parts (842, 844) dividing the frame part into the first frame part and the second frame part and configured to be opened or closed; optical unit accommodating part frames (840A, 840B) respectively formed at the first frame part and the second frame part; and an optical unit accommodating part formed at inner sides of the optical unit accommodating part frames (840A, 840B) and configured to be opened or closed as the filler is rotated about the rotating part, and an optical unit, wherein the filler is configured to be opened or closed by being rotated by a certain angle about the rotating part, wherein each of the first frame part and the second frame part comprises: an outer frame part formed in a circular arc shape; an inner frame part; and a support part configured to connect the outer frame part and the inner frame part, the cut parts and comprise: an upper cut part formed at the outer frame part; and a lower cut part formed at the inner frame part, wherein a length of the lower cut part is equal to or less than half an external diameter of the optical unit being accommodated in the optical unit accommodating part, wherein the rotating part is formed at an inner side of the inner frame part in a radial direction of the multicore cable such that the frame part is configured to be rotated to be opened or closed, and wherein a portion of the inner frame part is cut by the lower cut part and a non-cut portion thereof serves as the rotating part. a frame part including a first frame part and a second frame part which are symmetric to each other; a rotating part configured to connect the first frame part and the second frame part; cut parts (842, 844) dividing the frame part into the first frame part and the second frame part and configured to be opened or closed; optical unit accommodating part frames (840A, 840B) respectively formed at the first frame part and the second frame part; and an optical unit accommodating part formed at inner sides of the optical unit accommodating part frames (840A, 840B) and configured to be opened or closed as the filler is rotated about the rotating part, and an optical unit, wherein the filler is configured to be opened or closed by being rotated by a certain angle about the rotating part, wherein each of the first frame part and the second frame part comprises: an outer frame part formed in a circular arc shape; an inner frame part; and a support part configured to connect the outer frame part and the inner frame part, an outer frame part formed in a circular arc shape; an inner frame part; and a support part configured to connect the outer frame part and the inner frame part, the cut parts and comprise: an upper cut part formed at the outer frame part; and a lower cut part formed at the inner frame part, an upper cut part formed at the outer frame part; and a lower cut part formed at the inner frame part, wherein a length of the lower cut part is equal to or less than half an external diameter of the optical unit being accommodated in the optical unit accommodating part, wherein the rotating part is formed at an inner side of the inner frame part in a radial direction of the multicore cable such that the frame part is configured to be rotated to be opened or closed, and wherein a portion of the inner frame part is cut by the lower cut part and a non-cut portion thereof serves as the rotating part.