[Object] To make it possible to improve the accuracy of estimation of a user state further.[Solution] There is provided an information processing device including: a measurement unit configured to measure a first pupil diameter of a user； a calculation unit configured to calculate a reference pupil diameter on the basis of a condition for measuring the first pupil diameter； and an estimation unit configured to make an estimation of a state of the user on the basis of the first pupil diameter and the reference pupil diameter.
