A combustor includes an inner liner forming a combustion chamber; an outer liner surrounding the inner liner to form a cooling passage in which compressed air flows; and a plurality of cooling guides installed around an inner circumferential surface of the outer liner to surround the combustion chamber, each of the cooling guides protruding from the inner circumferential surface to create an impinging jet from the compressed air flowing in the cooling passage. The plurality of cooling guides surrounding the combustion chamber are installed at regular intervals in a flow direction of the compressed air, and are arranged in staggered axial rows. Each cooling guide includes an air guiding surface facing the flow of the compressed air to guide the compressed air toward the inner liner. Accordingly, liner cooling efficiency can be enhanced by more effectively guiding the impinging jet toward the inner liner.