A bag abnormality detection device includes a synchronous sensor, a first bag detection sensor, a second bag detection sensor and a controller. When the synchronous sensor detects a change, at a first detection point, from a state in which the bag is absent to a state in which the bag is present and the detection result of the first bag detection sensor indicates that the bag does not exist at a second detection point, the controller recognizes that the bag has an abnormality. When the synchronous sensor detects a change, at the first detection point, from a state in which the bag is present to a state in which the bag is absent and the detection result of the second bag detection sensor indicates that the bag does not exist at a third detection point, the controller recognizes that the bag has an abnormality.