A shoe purchase recommendation device includes: a user data storage unit that stores user data; a foot size change prediction unit that calculates a change prediction value of a foot size of the user on the basis of the user data; a product information storage unit that stores product information; a purchase recommendation processing unit that determines a purchase-recommended date and a purchase-recommended product of shoes on the basis of the change prediction value and the product information; and a screen display processing unit that performs processing of displaying, on a display unit, a foot size change diagram based on a foot size measurement value or the change prediction value from a past time point to the present and the change prediction value in a period from the present to a future time point, and a comparison value diagram indicating a comparison value of the foot size from the past time point to the future time point.