An information processing device comprises: an acceleration detector which detects an acceleration; a first traveling direction detector which detects a first traveling direction based on a detection result from the acceleration detector; an angular velocity detector which detects an angular velocity; a second traveling direction detector which detects a second traveling direction based on a detection result from the angular velocity detector; a traveling direction estimating unit which estimates a traveling direction of the information processing device based on a change in a traveling direction common to a change in the first traveling direction and a change in the second traveling direction; and a position estimating part which estimates a position of the information processing device based on an estimation result from the traveling direction estimating unit.