Pupillary responses may have potentials to evaluate a person's state of mind. Subjects (n= 17) viewed pictures, which could produce emotions (pleasant, neutral and unpleasant feeling), serially presented on an LCD with gray color images as ISI. We compared the pupil diameters on viewing gray images after emotional picture presentation. The pupil diameter after having pleasant feeling was significantly smaller than the diameter after viewing neutral pictures. On the contrary, pupil was significantly dilating after when the subjects had unpleasant feeling from the stimulus pictures. Those findings could be useful for evaluation of human state of mind.