PURPOSE: To automatically detect the leakage of a packaged fluid article by providing an electrode on the outer peripheral surfaces of rolls which press and carry the packaged fluid article.

CONSTITUTION: Two straps of spiral grooves are provided on the outer periphery of a roll 3 while putting a slight gap to each other, and electrodes 6, 7 of a copper wire are embedded in the grooves respectively. When a fluid pack P is fed between the upper and lower rolls 3 by a feeding device 5, the fluid pack P is pressed from the top and bottom by a specified pressure while being sent to the opposite side by the upper and lower rolls 3. If there is a defect such as an incompletely sealed part or flaw, etc., on the fluid pack P, a liquid inside flows out by the pressing, and the liquid adheres to the outer surface of the rolls 3. Since fluid generally has a conductivity, both electrodes 6, 7 are electrically connected by the adhered liquid, and the leakage is detected. Since the leakage which is inspected by one passing is mainly located at the rear area in the feeding direction, the front and rear of the pack P are inverted, and the pack P is inspected again by making it pass through between the rolls.