Provided are a method for manufacturing syngas including the steps of (S1) heat-treating organic waste in a first reactor to produce a first mixed gas; (S2) introducing the first mixed gas to a second reactor and subjecting it to methane reforming in the presence of a catalyst to produce a second mixed gas; (S3) separating the catalyst and carbon dioxide from the second mixed gas and recovering a third mixed gas from which the catalyst and the carbon dioxide have been removed; (S4) converting the carbon dioxide separated in step (S3) into carbon monoxide through a reverse Boudouard reaction in a third reactor; and (S5) mixing the third mixed gas recovered in step (S3) and the carbon monoxide converted in step (S4) to produce syngas, and an apparatus for manufacturing syngas.