A sliding door opening and closing device that horizontally opens and closes the sliding door with application of light weight is provided. A load-type door opening and closing device includes: a sliding support rail slidably supporting the door to open and close the door; a door opening rail provided in the door and inclined upward in an opening direction of the door; a sliding member sliding on the door opening rail; a footboard; and a coupling member that couples the sliding member with the footboard. The sliding member is located at an upper end side of the door opening rail when the door is closed, and is depressed against the door opening rail by stepping force acting on the footboard during opening operation, to displace the door in the opening direction.