Besides an input event reception unit 4 that receives an input such as a coordinate input event or the like and accumulates the coordinate input event or the like in an event queue 7, and an event executing device that performs the coordinate input event accumulated in the event queue 7, there are provided a drawing event reception unit 5 that receives a drawing event designating drawing contents on a screen, an update processing unit 14 that updates drawing contents in accordance with the drawing event received by the drawing event reception unit 5, and a drawing processing unit 16 that displays the drawing contents on the screen every time the drawing contents are updated.