Disclosed is a safety valve of a low-pressure gas pipe which can be installed in a large-scale pipeline through which waste gases generated in a large-scale factory such as a steel mill flow and can reduce maintenance/management costs. The safety valve of a low-pressure gas pipe installed in a waste gas pipeline to discharge condensate includes: a first pipeline connected to a bottom surface of the waste gas pipeline and having a waste gas outlet on an inner wall thereof at one side thereof; a second pipeline extending from the first pipeline to be bent and extending in a direction parallel to the first pipeline; and an opening/closing unit for opening or closing the waste gas outlet.