PROBLEM TO BE SOLVED: To provide a muscular strength measuring apparatus and method thereof in which measuring accuracy can be improved by equalizing the position of a sensor with the thickness of weights.SOLUTION: In the muscular strength measuring apparatus, one or more weights 26 are installed in an apparatus in which muscular strength is trained by pulling the weights with a wire 34. The apparatus includes: an installation pedestal part 40 that is arranged in a position comparable to the moving range of the weights 26 by being adjoined to the weights 26 with a prescribed interval; a light transmitting and receiving part 42 composed of a light emitting part which is installed in the installation pedestal part 40 in plurality with an equal interval to the thickness of the weights 26 respectively and which emits light, and composed of a light receiving part which receives reflected light of the light emitted by the light emitting part; a reflection part which is installed on the surface of the weights 26 cor
