An image forming apparatus including applications and system side software for providing system side services to the applications is provided, in which the image forming apparatus includes: an authentication module for displaying an authentication screen on an operation panel of the image forming apparatus, wherein the authentication module allows the image forming apparatus to display a screen for using the image forming apparatus instead of the authentication screen if authentication data input from the authentication screen satisfies an authentication condition, and wherein the authentication module is provided in the image forming apparatus separately from the system side software.