NOVELTY - The device has two pillars (11, 12) erected vertically on a lower plate support (10) comprising a predetermined area. A deflection length measuring unit (20) is integrally attached to one of the columns along the longitudinal direction to measure a deflection length of a gas diffusion layer (GDL) sample (50). A deflection length limit value sensor (30) determines whether the measured length has reached a threshold value. A GDL sample holder (40) is mounted at the top of the other column to accommodate an end of the GDL sample exhibiting a size equal to that of a GDL raw material plate.    USE - Device for non-destructive measurement of bending stiffness of a gas diffusion layer of a fuel cell e.g. polymer electrolyte membrane fuel cell (PEMFC), of a vehicle. Uses include but are not limited to a motor car e.g. passenger car, sport utility vehicle (SUV), bus, lorry, watercraft such as boats and ships, aircraft, hybrid vehicle, electric car, plug-in hybrid electric car and hydrogen-propelled vehicle.    ADVANTAGE - The GDL sample is obtained by cutting the GDL raw material plate so that the GDL sample used in the measurement is not damaged, thus enabling recycling of the sample in the assembly of a fuel cell stack, and hence reducing the inspection time by 40 to 120 times for preparing sample for the manufacturing of the fuel cell stack and for the measurement of the deflection length of the GDL sample, and improving the manufacturing efficiency of the fuel cell stack.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for a non-destructive measurement of bending stiffness of a gas diffusion layer of a fuel cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a device for measuring a deflection length of a GDL sample as a raw material sheet for non-destructive and indirect measurement of bending stiffness of a GDL.'(Drawing includes non-English language text)'    Lower plate support (10)    Pillars (11, 12)    Deflection length measuring unit (20)    Deflection length limit value sensor (30)    GDL sample holder (40)    GDL sample (50)