Quantifying walking stability is needed in order to evaluate the various walking assist methods. It can also allow the planning of individualized interventions for elderly people or patients with disorders. The Gait Sensitivity Norm (GSN) is a new measure of the walking stability developed for passive dynamic walkers and has been reported to show a strong correlation with the fall risk. The GSN is a method based on the idea of the H2 norm, which allows us to know the dynamic response of the system of walkers by measuring the impulse response. The reliability of the GSN quantification has been confirmed in passive dynamic walkers and neuromusculoskeletal walking models. However, it has not yet been applied to humans. In this paper, we proposed a method to apply the GSN to the analysis of human walking. To apply the GSN to a human gait, wearable sensors were used to analyze human walking. The validity of quantifying gait stability with the GSN is assessed in the experiments comparing abnormal walker (with some weight or blindfold) and normal walkers. The result is consistent with the intuitive idea that blind walking is more unstable than normal walking.