An image processing device includes an authenticator, an estimator, and a controller. The authenticator uses authentication information received from a user to authenticate and determine whether or not the user is a person allowed to execute plural functions related to images. If the authenticator authenticates the user as a registered user allowed to execute the plural functions, the estimator uses history information recording information related to the execution of the plural functions to estimate a function to be executed by the user from among the plural functions. The controller controls related parts used to execute the function estimated by the estimator so that the related parts start preparing for operation before the user issues an instruction to execute some kind of function.