The sliding door closing device, according to the invention, features an easy door opening function with an opening system comprising: a slider (2) with an attachment (25) and gripper (8) on one side, properly shaped support (5) of the moving roller (10a) on the other side, pusher (13) contacting the roller support (5) of the roller (10a) with a slider gripper (8) and the opening device spring (14) and choke (12). The opening system allows for the opening of a door by pushing the door on a vertical strip or on the edge.