A paint cartridge includes a baggy tank having a dual structure formed by an inner bag and an outer bag in a cylindrical body. Inside the inner bag is a paint chamber. Between the outer bag and the cylindrical body, an extruding liquid flows. A detector provided in the space between the inner bag and the outer bag is visually observable from outside the cylindrical body. In the detector, a pattern formed by using one or more materials changes due to contact with paint which leaks when the inner bag has broken or with extruding liquid which leaks when the outer bag has broken. In consequence, it is possible to detect the breakage of the inner bag and the outer bag by visually observing a change in the detector's pattern from the outside.