Having investigated an availability of testing methods for a large-capacity gas meter, the authors manufactured by way of trial a testing equipment for flow rates up to 200m³/h, which consists of a standard wet gas meter, changing valve and collapsible gas container which is made of compound rubber and has a capacity of about 5m³. Since its accuracy was found to be about ±0.1% from the result of experiments, they maufactured a larger testing equipment having a maximum capacity of about 30m3 and confirmed that it goes satisfactory even for larger flow rates up to 1500m³/h.