An information processing device for causing a user to feel as if a virtual object exists in a real space through sound image localization, the virtual object being a virtual character, comprising: a behavior deciding unit configured to decide virtual behavior of the virtual character in the real space in accordance with a recognized behavior of the user, and select a sound content (V1, V2, V3, V4, V5, V6, V7) corresponding to the decided behavior from a scenario as a sound image of the virtual object; a calculation unit configured to calculate: a localization position of the selected sound content relative to the user on the basis of information on the virtual object and information on a state of the user, and on the basis of the sound source type of the selected sound content (V1, V2, V3, V4, V5, V6, V7), wherein the sound source type of the sound content (V1, V2, V3, V4, V5, V6, V7) includes a voice sound source, a footstep sound source, a rustling clothing sound source, a belonging sound source, and a vehicle sound source; and a relative height at which the selected sound content (V1, V2, V3, V4, V5, V6, V7) is to be localized on the basis of a relative relation between a height (C1, C2, C3, C4) of a part of the virtual character corresponding to the sound source type and a height of an ear of the user based on the information on the state of the user, wherein the information on the state of the user includes an absolute position, a movement speed, a direction, a position of a head, and the height of an ear of the user, and the behaviour of the user recognized from them, and wherein the relative localization position of the selected sound content is a three-dimensional position including a height; the information processing device further comprising: a sound image localization unit configured to perform a sound signal process of the selected sound content such that the sound image is localized at the calculated localization position; and a sound output control unit configured to perform control such that a sound output unit plays back the sound signal processed by the sound image localization unit. a behavior deciding unit configured to decide virtual behavior of the virtual character in the real space in accordance with a recognized behavior of the user, and select a sound content (V1, V2, V3, V4, V5, V6, V7) corresponding to the decided behavior from a scenario as a sound image of the virtual object; a calculation unit configured to calculate: a localization position of the selected sound content relative to the user on the basis of information on the virtual object and information on a state of the user, and on the basis of the sound source type of the selected sound content (V1, V2, V3, V4, V5, V6, V7), wherein the sound source type of the sound content (V1, V2, V3, V4, V5, V6, V7) includes a voice sound source, a footstep sound source, a rustling clothing sound source, a belonging sound source, and a vehicle sound source; and a relative height at which the selected sound content (V1, V2, V3, V4, V5, V6, V7) is to be localized on the basis of a relative relation between a height (C1, C2, C3, C4) of a part of the virtual character corresponding to the sound source type and a height of an ear of the user based on the information on the state of the user, a localization position of the selected sound content relative to the user on the basis of information on the virtual object and information on a state of the user, and on the basis of the sound source type of the selected sound content (V1, V2, V3, V4, V5, V6, V7), wherein the sound source type of the sound content (V1, V2, V3, V4, V5, V6, V7) includes a voice sound source, a footstep sound source, a rustling clothing sound source, a belonging sound source, and a vehicle sound source; and a relative height at which the selected sound content (V1, V2, V3, V4, V5, V6, V7) is to be localized on the basis of a relative relation between a height (C1, C2, C3, C4) of a part of the virtual character corresponding to the sound source type and a height of an ear of the user based on the information on the state of the user, wherein the information on the state of the user includes an absolute position, a movement speed, a direction, a position of a head, and the height of an ear of the user, and the behaviour of the user recognized from them, and wherein the relative localization position of the selected sound content is a three-dimensional position including a height; the information processing device further comprising: a sound image localization unit configured to perform a sound signal process of the selected sound content such that the sound image is localized at the calculated localization position; and a sound output control unit configured to perform control such that a sound output unit plays back the sound signal processed by the sound image localization unit. a sound image localization unit configured to perform a sound signal process of the selected sound content such that the sound image is localized at the calculated localization position; and a sound output control unit configured to perform control such that a sound output unit plays back the sound signal processed by the sound image localization unit.