1. An image processing device comprising: a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute, acquiring a captured image; extracting a first feature amount and a second feature amount of a user included in the image, and a third feature amount indicative of a likelihood of a portion from which the second feature amount is extracted; generating 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; and selecting the third feature amount extracted at authentication of the user, and the first feature amount and the second feature amount included in the authentication table, based on the third feature amount included in the authentication table, and authenticating the user based on the first feature amount and the second feature amount which are selected, and the first feature amount and the second feature amount which are extracted at the authentication.