A device for checking the construction of an extruder screw having a shaft and screw elements that are to be pushed or have been pushed one after the other onto the shaft in a defined sequence. Each screw element has an element-specific external geometry. A recording device being provided for determining information concerning the sequence of the screw elements that are to be pushed on or have been pushed on and for comparing the information determined with target information, which directly or indirectly describes the target sequence.