A sound processing apparatus comprising: at least four sound outputting units (SP1, SP2, SP3, SP4); a gain calculating unit configured to determine ultimate output gains of sounds to be output from the at least four sound outputting units (SP1, SP2, SP3, SP4), the ultimate output gains being determined based on a positional relationship between the sound outputting units (SP1, SP2, SP3, SP4) with respect to each of different combinations among a plurality of combinations of three of the at least four sound outputting units (SP1, SP2, SP3, SP4), the at least four sound outputting units (SP1, SP2, SP3, SP4) being arranged to surround a sound image localization position, the sound image localization position being a target position for a sound image, the ultimate output gains being used for fixing the sound image at the sound image localization position; and a gain adjusting unit configured to perform gain adjustment on sounds to be output from the sound outputting units (SP1, SP2, SP3, SP4) based on the ultimate output gains, characterized in that the gain calculating unit includes: a virtual gain calculating unit (92-1, 92-2, 92-3, 92-4) configured to calculate output gains of three of the sound outputting units (SP1, SP2, SP3, SP4) based on a positional relationship among the three of the sound outputting units (SP1, SP2, SP3, SP4) and the sound image localization position; and a calculating unit configured to calculate ultimate output gains of the sound outputting units (SP1, SP2, SP3, SP4) based on the output gains calculated by the virtual gain calculating unit (92-1, 92-2, 92-3, 92-4) calculating the output gains with respect to different combinations among the combinations, wherein the calculating unit calculates an ultimate output gain of the same one of the sound outputting units (SP1, SP2, SP3, SP4) by determining a sum of the output gains determined with respect to the same one of the sound outputting units (SP1, SP2, SP3, SP4), and wherein at least four of the output gains each have a value other than 0. at least four sound outputting units (SP1, SP2, SP3, SP4); a gain calculating unit configured to determine ultimate output gains of sounds to be output from the at least four sound outputting units (SP1, SP2, SP3, SP4), the ultimate output gains being determined based on a positional relationship between the sound outputting units (SP1, SP2, SP3, SP4) with respect to each of different combinations among a plurality of combinations of three of the at least four sound outputting units (SP1, SP2, SP3, SP4), the at least four sound outputting units (SP1, SP2, SP3, SP4) being arranged to surround a sound image localization position, the sound image localization position being a target position for a sound image, the ultimate output gains being used for fixing the sound image at the sound image localization position; and a gain adjusting unit configured to perform gain adjustment on sounds to be output from the sound outputting units (SP1, SP2, SP3, SP4) based on the ultimate output gains, characterized in that the gain calculating unit includes: a virtual gain calculating unit (92-1, 92-2, 92-3, 92-4) configured to calculate output gains of three of the sound outputting units (SP1, SP2, SP3, SP4) based on a positional relationship among the three of the sound outputting units (SP1, SP2, SP3, SP4) and the sound image localization position; and a calculating unit configured to calculate ultimate output gains of the sound outputting units (SP1, SP2, SP3, SP4) based on the output gains calculated by the virtual gain calculating unit (92-1, 92-2, 92-3, 92-4) calculating the output gains with respect to different combinations among the combinations, wherein the calculating unit calculates an ultimate output gain of the same one of the sound outputting units (SP1, SP2, SP3, SP4) by determining a sum of the output gains determined with respect to the same one of the sound outputting units (SP1, SP2, SP3, SP4), and wherein at least four of the output gains each have a value other than 0. a virtual gain calculating unit (92-1, 92-2, 92-3, 92-4) configured to calculate output gains of three of the sound outputting units (SP1, SP2, SP3, SP4) based on a positional relationship among the three of the sound outputting units (SP1, SP2, SP3, SP4) and the sound image localization position; and a calculating unit configured to calculate ultimate output gains of the sound outputting units (SP1, SP2, SP3, SP4) based on the output gains calculated by the virtual gain calculating unit (92-1, 92-2, 92-3, 92-4) calculating the output gains with respect to different combinations among the combinations, wherein the calculating unit calculates an ultimate output gain of the same one of the sound outputting units (SP1, SP2, SP3, SP4) by determining a sum of the output gains determined with respect to the same one of the sound outputting units (SP1, SP2, SP3, SP4), and wherein at least four of the output gains each have a value other than 0.