An information processing device comprising: an acquisition unit configured to acquire a captured image; a detection unit configured to detect a plurality of targets included in the captured image; a discrimination unit configured to discriminate whether each of the plurality of detected targets is in a predetermined state, where the predetermined state is a state in which a person is looking at an object installed at a predetermined position; a reliability calculating unit configured to calculate the reliability of a discrimination result for each of the plurality of detected targets on the basis of the captured image; and an estimation unit configured to calculate the number of targets in the predetermined state, wherein the estimation unit is configured to: classify each of the plurality of detected targets into a first group for which the reliability is higher than a set value and a second group for which the reliability is lower than or equal to the set value; select a predetermined number of targets from among the first group in order from closest to each target belonging to the second group; determine whether the target belonging to the second group is in the predetermined state on the basis of a value obtained by multiplying each value expressing a discrimination result of each of the predetermined number of selected targets by an inverse number of a distance from the target to be determined as a weight and by totaling values expressing weighted discrimination results; and calculate the number of targets in the predetermined state on the basis of the discrimination result for each of the targets belonging to the first group and a determination result for each of the targets belonging to the second group. an acquisition unit configured to acquire a captured image; a detection unit configured to detect a plurality of targets included in the captured image; a discrimination unit configured to discriminate whether each of the plurality of detected targets is in a predetermined state, where the predetermined state is a state in which a person is looking at an object installed at a predetermined position; a reliability calculating unit configured to calculate the reliability of a discrimination result for each of the plurality of detected targets on the basis of the captured image; and an estimation unit configured to calculate the number of targets in the predetermined state, wherein the estimation unit is configured to: classify each of the plurality of detected targets into a first group for which the reliability is higher than a set value and a second group for which the reliability is lower than or equal to the set value; select a predetermined number of targets from among the first group in order from closest to each target belonging to the second group; determine whether the target belonging to the second group is in the predetermined state on the basis of a value obtained by multiplying each value expressing a discrimination result of each of the predetermined number of selected targets by an inverse number of a distance from the target to be determined as a weight and by totaling values expressing weighted discrimination results; and calculate the number of targets in the predetermined state on the basis of the discrimination result for each of the targets belonging to the first group and a determination result for each of the targets belonging to the second group. classify each of the plurality of detected targets into a first group for which the reliability is higher than a set value and a second group for which the reliability is lower than or equal to the set value; select a predetermined number of targets from among the first group in order from closest to each target belonging to the second group; determine whether the target belonging to the second group is in the predetermined state on the basis of a value obtained by multiplying each value expressing a discrimination result of each of the predetermined number of selected targets by an inverse number of a distance from the target to be determined as a weight and by totaling values expressing weighted discrimination results; and calculate the number of targets in the predetermined state on the basis of the discrimination result for each of the targets belonging to the first group and a determination result for each of the targets belonging to the second group.