To charge according to the quantity of used printing agent in a simple constitution.

Either of a dot count charge setting an identification method for every user and charging according to the estimation value of the quantity of toner used for the printing or a page count charge charging according to the number of printed paper sheets is set. Then, a user, the identification method, and the charge method are registered linked together. In printing, when the user identification is succeeded and the charge method set for the user is the dot count charge, a dot count value SUM is calculated based on the dot signal state in each pixel. For example, a value obtained by substituting corresponding values of (0, 1, and 2) for three value outputs of (0, 128, and 255) and totaling them is set to the SUM value, and the charge amount is calculated based on the SUM value.