Abstract: Provided is an object to be printed which can improve the quality of a printed image in inkjet printing on the object to be printed, regardless of the resolution of an inkjet image. In a method for producing an object to be printed having an area to be printed on a surface thereof, a surface of the area to be printed is adjusted so that the area to be printed has a surface energy E (mN/m) of 30 or more and 50 or less. The object to be printed is selected from a can and a film for containers.

Abstract: To enable a leakage inspection even without considering a change in a container temperature. A leakage inspection device includes a head mounting part that mounts inspection heads respectively on mouth parts of containers among containers alignedly conveyed from a container manufacturing line, a pressure supplying part that simultaneously feeds a supply pressure to the inspection heads respectively mounted on the containers to control pressure in the sealed containers to an inspection pressure, and a leakage determination part that detects a pressure change over time in the sealed containers and performs leakage determination of the containers. The leakage determination part includes a differential pressure sensor that detects a differential pressure in a pair of containers of the plurality of containers. The leakage determination part performs the leakage determination on the basis of an output of the differential pressure sensor.