Literary and aesthetic studies have suggested that readers can stay in indeterminate states where they hold multiple interpretations, and that this indeterminate interpretation state causes an aesthetic feeling, involvement, and understanding of art. To explore the indeterminate interpretation state, we employed a quantum cognition framework and conducted a reading experiment using a short story. The results suggest that readers' interpretations can be regarded as a superposition state corresponding to the indeterminate and polysemous interpretation of the story. We also estimated a time series of quantum indeterminacy and discussed the text features related to quantum indeterminacy.