A vehicle mounted offset value computation unit comprising: an acquisition unit configured to acquire positioning data for a vehicle positioned based on a signal from a GPS satellite, an angular speed of the vehicle output from an angular speed sensor, and a temperature of the vehicle output from a temperature sensor; a condition estimation unit configured to estimate a traveling condition of the vehicle; an condition-specific offset value derivation unit configured to derive a temporary offset value of the angular speed sensor in accordance with the traveling condition of the vehicle estimated in the condition estimation unit based on the positioning data and the angular speed acquired by the acquisition unit; and an offset temperature-dependent property correction unit configured to derive the offset value of the angular speed sensor based on the temporary offset value of the angular speed sensor derived by the condition-specific offset value derivation unit and the temperature acquired by the acquisition unit, wherein the offset temperature-dependent property correction unit comprises: a temperature gradient calculation unit configured to calculate a temperature gradient (γTn) based on the temperature acquired by the acquisition unit and to calculate an average temperature based on the temperature gradient (γTn); an offset gradient calculation unit configured to calculate an offset value gradient (yGn) based on the average temperature calculated by the temperature gradient calculation unit and on the temporary offset value of the angular speed sensor derived by the condition-specific offset value derivation unit; and a correction value calculation unit configured to calculate the offset value of the angular speed sensor based on the offset value gradient (yGn) calculated by the offset gradient calculation unit and the temperature gradient (γTn) calculated by the temperature gradient calculation unit, wherein the temperature gradient calculation unit adjusts a period of time that should elapse before the temperature gradient (γTn) is derived next time based on the temperature gradient (γTn) already derived. an acquisition unit configured to acquire positioning data for a vehicle positioned based on a signal from a GPS satellite, an angular speed of the vehicle output from an angular speed sensor, and a temperature of the vehicle output from a temperature sensor; a condition estimation unit configured to estimate a traveling condition of the vehicle; an condition-specific offset value derivation unit configured to derive a temporary offset value of the angular speed sensor in accordance with the traveling condition of the vehicle estimated in the condition estimation unit based on the positioning data and the angular speed acquired by the acquisition unit; and an offset temperature-dependent property correction unit configured to derive the offset value of the angular speed sensor based on the temporary offset value of the angular speed sensor derived by the condition-specific offset value derivation unit and the temperature acquired by the acquisition unit, wherein the offset temperature-dependent property correction unit comprises: a temperature gradient calculation unit configured to calculate a temperature gradient (γTn) based on the temperature acquired by the acquisition unit and to calculate an average temperature based on the temperature gradient (γTn); an offset gradient calculation unit configured to calculate an offset value gradient (yGn) based on the average temperature calculated by the temperature gradient calculation unit and on the temporary offset value of the angular speed sensor derived by the condition-specific offset value derivation unit; and a correction value calculation unit configured to calculate the offset value of the angular speed sensor based on the offset value gradient (yGn) calculated by the offset gradient calculation unit and the temperature gradient (γTn) calculated by the temperature gradient calculation unit, wherein a temperature gradient calculation unit configured to calculate a temperature gradient (γTn) based on the temperature acquired by the acquisition unit and to calculate an average temperature based on the temperature gradient (γTn); an offset gradient calculation unit configured to calculate an offset value gradient (yGn) based on the average temperature calculated by the temperature gradient calculation unit and on the temporary offset value of the angular speed sensor derived by the condition-specific offset value derivation unit; and a correction value calculation unit configured to calculate the offset value of the angular speed sensor based on the offset value gradient (yGn) calculated by the offset gradient calculation unit and the temperature gradient (γTn) calculated by the temperature gradient calculation unit, wherein the temperature gradient calculation unit adjusts a period of time that should elapse before the temperature gradient (γTn) is derived next time based on the temperature gradient (γTn) already derived.