The objective of the present invention is to provide a substrate cutting system which requires a small footprint area so as to be compact, and also which is capable of efficiently cutting a substrate. Clamp devices 50 are attached to the substrate cutting system. The clamp devices can hold at least one part of a side edge of the mother substrate to be carried-in a mounting base 10 in a hollow rectangular parallelepiped and reciprocate along one side of the mounting base 10 in a hollow rectangular parallelepiped. A pair of substrate cutting devices are provided in a cutting device guide body 30 so as to be movable along a direction perpendicular to the moving direction of the clamp devices 50, the pair of substrate cutting devices cutting the mother substrate from each of the top surface and the bottom surface of the mother substrate which is clamped by the clamp devices 50. When the clamp devices 50 holding the mother substrate are moved, a substrate supporting device supports the mother substrate without rubbing against the mother substrate.