There is provided an information processing device including a control unit that determines reliability of positioning information of a user calculated on a basis of sensed information output from a sensing unit built in a portable information processing device. According to the present disclosure, it is possible to determine the reliability of positioning information. Note that the effects described above are not necessarily limitative. With or in the place of the above effects, there may be achieved any one of the effects described in this specification or other effects that may be grasped from this specification.