A method for checking a value document of a specified type for the suspected presence of a forgery, in particular of a pieced-together forgery, - wherein at least one ultrasonic property of the value document is captured in a spatially resolved manner so as to form location-dependent measuring data, - wherein while employing the location-dependent measuring data it is checked whether two areal regions (62, 64; 64; 68; 72, 74) are present in a specified checking region (64; 80) of the value document, so that the at least one ultrasonic property has a specified first course at locations in a first one of the two areal regions (62, 64; 64, 68; 72, 74), and the at least one ultrasonic property in the first areal region (62, 64; 64, 68; 72, 74) and the at least one ultrasonic property in the other areal region (62, 64; 64, 68; 72, 74) deviate from each other according to a specified difference criterion, - when checking whether the two areal regions (62, 64; 64, 68; 72, 74) are present in the specified checking region (64; 80) of the value document, averages over the measuring data over at least three neighboring locations are formed and employed for establishing the course in the first areal region (62, 64; 64, 68; 72, 74) and/or when checking the distinguishing criterion and/or when checking whether the two areal regions are present, only those areal regions (62, 64; 64, 68; 72, 74) are taken into consideration whose surface areas exceed a specified minimum surface area, and - wherein there is formed an authenticity signal which represents the result of the check and corresponds to an indication of a pieced-together forgery, when the distinguishing criterion is satisfied. - wherein at least one ultrasonic property of the value document is captured in a spatially resolved manner so as to form location-dependent measuring data, - wherein while employing the location-dependent measuring data it is checked whether two areal regions (62, 64; 64; 68; 72, 74) are present in a specified checking region (64; 80) of the value document, so that the at least one ultrasonic property has a specified first course at locations in a first one of the two areal regions (62, 64; 64, 68; 72, 74), and the at least one ultrasonic property in the first areal region (62, 64; 64, 68; 72, 74) and the at least one ultrasonic property in the other areal region (62, 64; 64, 68; 72, 74) deviate from each other according to a specified difference criterion, - when checking whether the two areal regions (62, 64; 64, 68; 72, 74) are present in the specified checking region (64; 80) of the value document, averages over the measuring data over at least three neighboring locations are formed and employed for establishing the course in the first areal region (62, 64; 64, 68; 72, 74) and/or when checking the distinguishing criterion and/or when checking whether the two areal regions are present, only those areal regions (62, 64; 64, 68; 72, 74) are taken into consideration whose surface areas exceed a specified minimum surface area, and - wherein there is formed an authenticity signal which represents the result of the check and corresponds to an indication of a pieced-together forgery, when the distinguishing criterion is satisfied.