Providing an apparatus for detecting gas leakage from the periphery of a cylinder valve or the like of a plurality of gas cylinders, non-manually in a short time without failure, in place of manual detection.The apparatus for detecting gas leakage from a plurality of gas cylinders is characterized in that the apparatus is constructed such that one end of each of flexible hoses (2) is connected to each cap (1) put on a plurality of gas cylinders, the other end of each of flexible hoses is connected to one of the faces of an assembly panel (3), another flexible hose (4) is led out of the other face of the assembly panel and connected to a detector (6), a gas aspirator (5) for sucking gas from the cap, is connected upstream or downstream of the detector (6), and these apparatuses are controlled by a controller (7).