A slide assist system provided between sliding surfaces of a fixed housing and a movable housing provided with a spring, endpiece members swingably attached to the two ends of the spring, two parallel ridges each is provided sticking out at the fixed housing and the movable housing, wherein the spring is expanded or contracted to insert it in a clearance between the two parallel ridges, one of the endpiece members is made to engage with an engagement part of the fixed housing side ridge, the other is made to engage with an engagement part of the movable housing side ridge, and, in the state where the fixed housing and the movable housing are superposed and the state where they are slid, the engagement part of the fixed housing side ridge and the engagement part of the movable housing side ridge which engage with the same endpiece member are switched.