The present invention relates to a method for determining illustrations for a diaper to be worn, for example, by an infant. With the present invention's illustration determination method, for a diaper, comprising a main body, fitted onto the body of an infant, and an illustration displaying part, provided on the main body for displaying an illustration, the abovementioned illustration is determined based on the age in months of the infant. The illustration can arouse interest of an infant definitely since the object of interest of an infant depends on his/her age in months. An infant can thus be made to calm down during diaper exchange and the labor of diaper exchange can be alleviated.