An image processing device comprising: an acquisition unit operable to acquire a captured image; an extraction unit operable to extract: a color histogram of a face region, or both the face region and a body region, of a user included in the captured image, as a first feature amount; a feature amount vector of the face region, as a second feature amount; and using a method for detecting the face of the user in the captured image, a face-detection likelihood of the face region as a third feature amount that is indicative of a likelihood of a portion from which the second feature amount is extracted, the third feature amount having a larger value when the face region of the user faces the front than when the face region of the user faces a lateral direction other than the front; a generation unit operable to generate an authentication table including a plurality of the first feature amounts, a plurality of the second feature amounts, and a plurality of the third feature amounts extracted from a plurality of the images acquired by the acquisition unit; and an authentication unit operable to select a first feature amount and a second feature amount included in the authentication table, based on a comparison of the third feature amounts included in the authentication table with a third feature amount extracted at authentication of the user, and authenticate the user based on a comparison of the selected first feature amount and the selected second feature amount with a first feature amount and a second feature amount which are extracted at the authentication, respectively. an acquisition unit operable to acquire a captured image; an extraction unit operable to extract: a color histogram of a face region, or both the face region and a body region, of a user included in the captured image, as a first feature amount; a feature amount vector of the face region, as a second feature amount; and using a method for detecting the face of the user in the captured image, a face-detection likelihood of the face region as a third feature amount that is indicative of a likelihood of a portion from which the second feature amount is extracted, the third feature amount having a larger value when the face region of the user faces the front than when the face region of the user faces a lateral direction other than the front; a color histogram of a face region, or both the face region and a body region, of a user included in the captured image, as a first feature amount; a feature amount vector of the face region, as a second feature amount; and using a method for detecting the face of the user in the captured image, a face-detection likelihood of the face region as a third feature amount that is indicative of a likelihood of a portion from which the second feature amount is extracted, the third feature amount having a larger value when the face region of the user faces the front than when the face region of the user faces a lateral direction other than the front; a generation unit operable to generate an authentication table including a plurality of the first feature amounts, a plurality of the second feature amounts, and a plurality of the third feature amounts extracted from a plurality of the images acquired by the acquisition unit; and an authentication unit operable to select a first feature amount and a second feature amount included in the authentication table, based on a comparison of the third feature amounts included in the authentication table with a third feature amount extracted at authentication of the user, and authenticate the user based on a comparison of the selected first feature amount and the selected second feature amount with a first feature amount and a second feature amount which are extracted at the authentication, respectively.