Provided is an image forming apparatus and a method, an abnormal nozzle detection method, and a printed matter manufacturing method that can suppress the consumption of an extra medium and can efficiently specify an abnormal nozzle. The image forming apparatus (10) includes a print head (16) that has a plurality of nozzles, an association unit (40) that associates the nozzle with a partial region in a user image, a first correction unit that performs a first correction assuming that the associated nozzle is abnormal in at least one of the partial regions, a streak detection unit (44) that detects streak information from a print result of the user image including the partial region subjected to the first correction, and a nozzle state estimation unit (46) that estimates a state of the nozzle on the basis of the streak information of two or more partial regions in a single user image.