A method of selecting patients highly responsive to WT1 vaccine and a therapeutic method for treating cancer involving said method of selection are provided, which method of selecting patients highly responsive to WT1 vaccine comprises: (a) isolating a biological sample containing CTL precursor cells from a test subject； (b) measuring the existence frequency or amount of WT1-specific CTL precursor cells in the biological sample of (a)； and (c) deciding whether or not the measured value of (b) is high by comparison with that of healthy subject, and evaluating the responsiveness to WT1 vaccine.
