1. An item recommendation method comprising: generating a rating matrix based on a relationship between a user and an item; wherein the rating matrix including rated items determined based on a post-use preferences, generating an observed pre-use preference matrix by changing the post-use preference for a rated item in the rating matrix; inferring a pre-use preference for a unrated item in the rating matrix; determining a pre-use preference matrix by applying the inferred pre-use preference for the unrated item into the observed pre-use preference matrix; and generating a zero-injected matrix using the rating matrix and the pre-use preference matrix.