Abstract: Apparatus for measuring the mechanical strength of a neck portion of a silicon seed crystal used for growing a silicon crystal by the Czochralski method includes a seed chuck for holding the seed crystal of a test sample and an end of a wire hung from an upper hook. A crystal holder which holds the other end part of the test sample from below is tied to a lower hook with another wire to support the holder. The apparatus includes means for pulling the hook at a given rate, and measuring means for continuously measuring tensile load. Such apparatus and the method thereby provide accurate measurement of mechanical strength of the neck portion of the silicon seed crystal with good precision and reproducibility. A single crystal ingot is grown under conditions affording good balance of productivity and safety.