An own-position estimating device for estimating an own-position of a moving body by matching a feature extracted from an acquired image with a database in which position information items link position information, a division pattern, light-dark determination threshold values, and feature numbers associated with each other in advance, the device comprising: a storage unit configured to store said database; an image acquiring unit configured to acquire the image; an extracting unit configured to extract the feature from the image acquired by the image acquiring unit; an estimating unit configured to estimate the own-position of the moving body by matching the feature extracted by the extracting unit with the database; and a determination threshold value adjusting unit configured to: - acquire the database in a state in which the light-dark determination threshold value is adjusted, - to adjust the light-dark determination threshold values by: -- inputting an image as the basis for adjustment; -- dividing the image into a plurality of areas according to a division pattern; -- adjusting for each divided area a corresponding light-dark determination threshold value; -- determining the number of features with respect to each divided area, -- determining whether or not the number of features falls within a constant range; -- and, if it is determined that the number of features falls within the constant range with respect to all divided areas, by linking and registering in the database the position information, the division pattern, the light-dark determination threshold values, and the feature numbers, and wherein the extracting unit is configured to extract the feature from the image by using the light-dark determination threshold value adjusted by the determination threshold value adjusting unit. a storage unit configured to store said database; an image acquiring unit configured to acquire the image; an extracting unit configured to extract the feature from the image acquired by the image acquiring unit; an estimating unit configured to estimate the own-position of the moving body by matching the feature extracted by the extracting unit with the database; and a determination threshold value adjusting unit configured to: - acquire the database in a state in which the light-dark determination threshold value is adjusted, - to adjust the light-dark determination threshold values by: -- inputting an image as the basis for adjustment; -- dividing the image into a plurality of areas according to a division pattern; -- adjusting for each divided area a corresponding light-dark determination threshold value; -- determining the number of features with respect to each divided area, -- determining whether or not the number of features falls within a constant range; -- and, if it is determined that the number of features falls within the constant range with respect to all divided areas, by linking and registering in the database the position information, the division pattern, the light-dark determination threshold values, and the feature numbers, - acquire the database in a state in which the light-dark determination threshold value is adjusted, - to adjust the light-dark determination threshold values by: -- inputting an image as the basis for adjustment; -- dividing the image into a plurality of areas according to a division pattern; -- adjusting for each divided area a corresponding light-dark determination threshold value; -- determining the number of features with respect to each divided area, -- determining whether or not the number of features falls within a constant range; -- and, if it is determined that the number of features falls within the constant range with respect to all divided areas, by linking and registering in the database the position information, the division pattern, the light-dark determination threshold values, and the feature numbers, -- inputting an image as the basis for adjustment; -- dividing the image into a plurality of areas according to a division pattern; -- adjusting for each divided area a corresponding light-dark determination threshold value; -- determining the number of features with respect to each divided area, -- determining whether or not the number of features falls within a constant range; -- and, if it is determined that the number of features falls within the constant range with respect to all divided areas, by linking and registering in the database the position information, the division pattern, the light-dark determination threshold values, and the feature numbers,