A combustor comprising: a plurality of combustion nozzles; a cooling chamber configured to surround the plurality of combustion nozzles; an inner liner configured to surround one end of the cooling chamber and to have a plurality of through-holes formed in a circumferential direction in an end region surrounding the one end of the cooling chamber; an outer liner configured to surround the inner liner and to be spaced apart from the inner liner at a predetermined interval; a plurality of protrusions configured to be disposed so as to be spaced apart from each other in the circumferential direction on an outer circumferential surface of the inner liner in the end region, wherein each of the plurality of protrusions comprises: a support block configured to be connected to the outer circumferential surface of the inner liner, and an insertion block configured to be disposed on the support block with only a portion of a lower surface of the insertion block being in contact with the support block such that the insertion block is spaced apart from the outer circumferential surface of the inner liner and overlapping, in a direction vertical to the outer circumferential surface of the inner liner, with a virtual line connecting the plurality of through-holes when viewed from a direction from the inner liner toward the outer liner; and a plurality of accommodation portions configured to be disposed on an inner circumferential surface of the outer liner so as to respectively correspond to the plurality of protrusions and to respectively accommodate the plurality of protrusions. a plurality of combustion nozzles; a cooling chamber configured to surround the plurality of combustion nozzles; an inner liner configured to surround one end of the cooling chamber and to have a plurality of through-holes formed in a circumferential direction in an end region surrounding the one end of the cooling chamber; an outer liner configured to surround the inner liner and to be spaced apart from the inner liner at a predetermined interval; a plurality of protrusions configured to be disposed so as to be spaced apart from each other in the circumferential direction on an outer circumferential surface of the inner liner in the end region, wherein each of the plurality of protrusions comprises: a support block configured to be connected to the outer circumferential surface of the inner liner, and an insertion block configured to be disposed on the support block with only a portion of a lower surface of the insertion block being in contact with the support block such that the insertion block is spaced apart from the outer circumferential surface of the inner liner and overlapping, in a direction vertical to the outer circumferential surface of the inner liner, with a virtual line connecting the plurality of through-holes when viewed from a direction from the inner liner toward the outer liner; and a plurality of accommodation portions configured to be disposed on an inner circumferential surface of the outer liner so as to respectively correspond to the plurality of protrusions and to respectively accommodate the plurality of protrusions. a support block configured to be connected to the outer circumferential surface of the inner liner, and an insertion block configured to be disposed on the support block with only a portion of a lower surface of the insertion block being in contact with the support block such that the insertion block is spaced apart from the outer circumferential surface of the inner liner and overlapping, in a direction vertical to the outer circumferential surface of the inner liner, with a virtual line connecting the plurality of through-holes when viewed from a direction from the inner liner toward the outer liner; and a plurality of accommodation portions configured to be disposed on an inner circumferential surface of the outer liner so as to respectively correspond to the plurality of protrusions and to respectively accommodate the plurality of protrusions.