Disclosed herein is an automatic closing apparatus for a sliding apparatus. The sliding apparatus comprises a fixed rail, a movable rail, and the automatic closing apparatus. The automatic closing apparatus includes a body, a slider, a housing, a damping unit, and an elastic body. The body is provided on the fixed rail and has an actuating space therein. The body includes: a guide wall that is provided in the actuating space and includes a curved guide part and a linear guide part; and a receiving space formed adjacent to the curved guide part. The slider is locked to or unlocked from a locking member of the movable rail and slides in an open or close direction under guide of the guide wall. The housing is coupled to the body. The damping unit is installed in the housing. The elastic body is fastened to the housing and the slider.