To provide a strength evaluating method which can correctly evaluate the strength of a metal frame by a frame model which can be easily and inexpensively manufactured in evaluating the strength of the symmetric metal frame using the frame model.

The method for evaluating the strength of the symmetric first metal frame 20, and the strength of the symmetric second metal frame 30 in which the configuration of a left portion 36 and a right portion 37 is different from the configuration of a left portion 26 and a right portion 27 of the first frame using the single frame model 40, comprises steps 1-3 of the manufacturing process for trial manufacture of the frame model 40 in which a left portion 46 thereof is of a structure corresponding to the left portion 26 and the right portion 27 of the first frame 20, and a right portion 47 thereof is of a structure corresponding to the left portion 36 and the right portion 37 of the second frame 30, steps 4-6 of the testing process for measurement of the strength of the left portion 46 and the right portion 47 of the frame model 40, and a step 7 of the evaluation process to respectively evaluate the strength of the left portion 46 and the right portion 47 of the frame model 40.