The invention relates to a method for a method for continuous production control of sandwich panels, which panels are made by attaching a prefabricated thermal insulation core section of structural mineral wool to surface boards of the panels. The method comprises cutting the prefabricated structural mineral wool into a strip-like test specimen (15), having certain dimensions in various directions; placing said strip being in a measuring apparatus (1) for shearing strength, said apparatus comprising a mobile clamping element (2) and alongside the same at least one immobile clamping element (3), each provided with a cavity (2a, 3a) capable of receiving part of the strip-like test specimen (15); applying, normal to the lengthwise direction of the specimen, a force F to the mobile head for moving the mobile clamping element (2) relative to the immobile clamping element (3) for achieving the shearing of the presently measured strip (15) at a location (14) between the mobile clamping element (2) and the immobile clamping element (3); measuring said force F for its magnitude, and determining the shearing strength of the core section on the basis thereof; and calculating the shearing strength of the final sandwich panel product by using a calibration factor determined experimentally or mathematically and using this calculated shearing strength as a control parameter.