A process for manufacturing a fluid, including the steps of punching spout or outlet plug fitting holes in both a plate of a tubular blank of the carton and a plastic film constituting the internal bag at a predetermined place where a spout or outlet plug is attached to the tubular blank and the internal bag, the tubular blank containing the plastic film and having a closed bottom wall, fitting the spout or outlet plug in the spout or outlet plug fitting holes from inside the tubular plug, and welding the spout or outlet plug to the plastic film. An apparatus of manufacturing a fluid container, including a circulating conveyor conveying a tubular blank of the carton, the tubular blank containing a plastic film constituting the internal bag, and having a closed bottom wall, a punch cutting spout or outlet plug fitting holes in predetermined portions of a plate of the tubular blank and the plastic film which have been delivered by the circulating conveyor to a predetermined place, and a spout or outlet plug welder provided downstream of the punch and welding the spout or outlet plug which has been fitted in the spout or outlet plug fitting holes to the tubular blank and the plastic film which have been delivered by the circulating conveyor to a predetermined place.